This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Arabic verbs" – news ·newspapers ·books ·scholar ·JSTOR(June 2012) (Learn how and when to remove this message)

Arabic verbs (فِعْلfiʿl;pl.أَفْعَالafʿāl), like the verbs in otherSemitic languages, and the entire vocabulary in those languages, are based on a set of two to five (but usually three) consonants called aroot (triliteral orquadriliteral according to the number of consonants). The root communicates the basic meaning of the verb, e.g.ك-ت-بk-t-b 'write',ق-ر-ءq-r-ʾ 'read',ء-ك-لʾ-k-l 'eat'. Changes to the vowels in between the consonants, along with prefixes or suffixes, specify grammatical functions such as person, gender, number, tense, mood, and voice.

Various categories are marked on verbs:

• Threetenses (present, past; future tense is indicated by the prefixsa- or the particlesawfa and the present tense).
• Twovoices (active, passive)
• Twogenders (masculine, feminine)
• Threepersons (first, second, third)
• Threenumbers (singular,dual, plural)
• Sixmoods in the non-past only (indicative,subjunctive,jussive,imperative, and short and longenergetics)
• Nineteen forms, the derivational systems indicating derivative concepts such asintensive,causative,reciprocal,reflexive,frequentative etc. For each form, there is also an active and a passiveparticiple (both adjectives, declined through the full paradigm of gender, number, case and state) and averbal noun (declined for case; also, when lexicalized, may be declined for number).

Weakness is an inherent property of a given verb determined by the particular consonants of the verb root (corresponding to averb conjugation inClassical Latin and other European languages), with five main types of weakness and two or three subtypes of each type.

Arabic grammarians typically use the rootف-ع-لf-ʿ-l to indicate the particular shape of any given element of a verbal paradigm. As an example, the formيتكاتب (root: ك-ت-ب)yutakātabu 'he is corresponded (with)' would be listed generically asيتفاعلyutafāʿalu (yuta1ā2a3u), specifying the generic shape of a strong Form VI passive verb, third-person masculine singular present indicative.

The maximum possible total number of verb forms derivable from a root — not counting participles and verbal nouns — is approximately 13 person/number/gender forms; times 9 tense/mood combinations, counting the س-sa- future (since the moods are active only in the present tense, and the imperative has only 5 of the 13 paradigmatic forms); times 17 form/voice combinations (since forms IX, XI–XV exist only for a small number of stative roots, and form VII cannot normally form a passive), for a total of 1,989. Each of these has its own stem form, and each of these stem forms itself comes in numerous varieties, according to the weakness (or lack thereof) of the underlying root.

Each particularlexical verb is specified by four stems, two each for theactive andpassive voices. In a particular voice, one stem (theperfective stem) is usually used for the past tense, and the other (theimperfective stem) is usually used for thepresent andfuture tenses, along with non-indicativemoods, e.g.subjunctive andimperative. Though there is still some disagreement about the interpretation of the stems as tense or aspect, the dominant current view is that the stems represent aspect, sometimes of a relative rather than absolute nature. In this system of classification, the ostensibly "past" and "non-past" stems are called theperfective stem andimperfective stem.^[1]

To the past stem, suffixes are added to mark the verb for person, number and gender, while to the non-past stem, a combination of prefixes and suffixes are added. (Very approximately, the prefixes specify the person and the suffixes indicate number and gender.) A total of 13 forms exist for each of the two stems, specifying person (first, second or third); number (singular, dual or plural); and gender (masculine or feminine).

There are six separate moods in the non-past:indicative,imperative,subjunctive,jussive, shortenergetic and longenergetic. The moods are generally marked by suffixes. When no number suffix is present, the endings are-u for indicative,-a for subjunctive, no ending for imperative and jussive,ـَنْ-an for shorter energetic,ـَنَّ-anna for longer energetic. When number suffixes are present, the moods are either distinguished by different forms of the suffixes (e.g.ـُونَ-ūna for masculine plural indicative vs.ـُو-ū for masculine plural subjunctive/imperative/jussive), or not distinguished at all. The imperative exists only in the second person and is distinguished from the jussive by the lack of the normal second-person prefixـتta-/tu-.

The third person masculine singular past tense form serves as the "dictionary form" used to identify a verb, similar to theinfinitive in English. (Arabic has no infinitive.) For example, the verb meaning 'write' is often specified asكَتَبَkataba, which actually means 'he wrote'. This indicates that the past-tense stem isكَتَبْـkatab-; the corresponding non-past stem isـكْتُبْـ-ktub-, as inيَكْتُبُyaktubu 'he writes'. Using the third person masculine singular as the dictionary citation form is more useful in that the vowels that appear in the remaining present tense forms are evident. Especially in form I verbs, without prior knowledge, these vowels are often not evident based purely on the past-tense forms.

There are three tenses in Arabic: the past tense (اَلْمَاضِيal-māḍī), the present tense (اَلْمُضَارِعal-muḍāriʿ) and the future tense. The future tense in Classical Arabic is formed by adding either the prefix ‏سَـ‎sa- or the separate word ‏سَوْفَ‎sawfa onto the beginning of the present tense verb, e.g.سَيَكْتُبُsa-yaktubu orسَوْفَ يَكْتُبُsawfa yaktubu 'he will write'.

In some contexts, the tenses representaspectual distinctions rather than tense distinctions. The usage of Arabic tenses is as follows:

• The past tense often (but not always) specifically has the meaning of a pastperfective, i.e. it expresses the concept of 'he did' as opposed to 'he was doing'. The latter can be expressed using the combination of the past tense of the verbكَانَkāna 'to be' with the present tense or active participle, e.g.كَانَ يَكْتُبُkāna yaktubu orكَانَ كَاتِبٌkāna kātibun 'he was writing'. There are some special verbs known as "compound verbs" that can express manygrammatical aspects such asInchoative,Durative etc., for exampleبَدَأ يُلْفِتُ النَظرَbadaʾa yulfitu al-naẓara means "he started to attract attention" whichbadaʾa conveys the meaning of "to start doing something (in the past)"
• The two tenses can be used to express relative tense (or in an alternative view, grammatical aspect) when following other verbs in aserial verb construction. In such a construction, the present tense indicates time simultaneous with the main verb, while the past tense indicates time prior to the main verb. (Or alternatively, the present tense indicates theimperfective aspect while the past tense indicates theperfective aspect.)

In all but Form I, there is only one possible shape for each of the past and non-past stems for a given root. In Form I, however, different verbs have different shapes. Examples:

• كَتَبَ يَكْتُبُkataba yaktubu 'write'
• كَسَبَ يَكْسِبُkasaba yaksibu 'earn'
• قَرَأَ يَقْرَأُqaraʾa yaqraʾu 'read'
• قَدِمَ يَقْدَمُqadima yaqdamu 'turn'
• كَبُرَ يَكْبُرُkabura yakburu 'become big, grow up'

Notice that the second vowel can be any ofa i u in both past and non-past stems. The vowela occurs in most past stems, whilei occurs in some (especiallyintransitive) andu occurs only in a fewstative verbs (i.e. whose meaning is 'be X' or 'become X' where X is an adjective). The most common patterns are:

• past:a; non-past:u ori
• past:a, non-past:a (when the second or third root consonant is a "guttural," i.e. one ofʾ ʿ h ḥ)
• past:i; non-past:a
• past:u; non-past:u

There are three moods (حَالَاتḥālāt, a word that also means "cases";sg. ‏حَالَة‎ḥālah), whose forms are derived from the imperfective stem: theindicative mood (‏مَرْفُوع‎marfūʿ), usually ending inu; thesubjunctive (‏مَنْصُوب‎manṣūb), usually ending ina; and thejussive (‏مَجْزُوم‎majzūm), with no ending. In less formal Arabic and in spoken dialects, the subjunctive mood is used as the only imperfective tense (subjunctivism) and the final ḥarakah vowel is not pronounced.

Theimperative (صِيغَة اَلْأَمْرṣīghat al-amr) (positive, only 2nd person) is formed by dropping the verbal prefix (ت-) from the imperfective jussive stem, e.g.قَدِّمqaddim 'present!'. If the result starts with two consonants followed by a vowel (a ori), anelidiblealif (ا) is added to the beginning of the word, usually pronounced as "i", e.g.اِغْسِلْighsil 'wash!' orاِفْعَلifʿal 'do!' if the present form vowel isu, then the alif is also pronounced asu, e.g.أُكْتُبuktub 'write!'. Negative imperatives are formed from the jussive.

The exception to the above rule is the form (or stem) IV verbs. In these verbs a non-elidible alif ا pronounced asa- is always prefixed to the imperfect jussive form, e.g.أرسلarsil "send!",أضف^[2]aḍif 'add!'.

The subjunctive is used in subordinate clauses after certain conjunctions. The jussive is used in negation, in negative imperatives, and in the hortativela+jussive. For example: 2.sg. m.:

• imperfect indicativeتفعلُtafʿalu 'you are doing'
• subjunctiveأن تفعلَan tafʿala 'that you do'
• jussiveلا تفعلْlā tafʿal its meaning is dependent upon the prefix which attaches to it; in this case, it means 'may you do not do!'
• short energeticتفعلنْtafʿalan its meaning is dependent upon the prefix which attaches to it; if the prefix is "la" it means 'you should do'
• long energeticتفعلنَّtafʿalanna it has more emphasis than the short energetic, its meaning is dependent upon the prefix which attaches to it; if the prefix is "la" it means 'you must do'
• imperativeافعلifʿal 'do!'.

Arabic has two verbalvoices (صِيغَاتṣīghāt "forms",sg.صِيغَةṣīghah),active (صِيغَة اَلْمَعْلُومṣīghat al-maʿlūm), andpassive (صِيغَة اَلْمَجْهُولṣīghat al-majhūl). The passive voice is expressed by a change in vocalization. For example:

• activeفَعَلَfaʿala 'he did',يَفْعَلُyafʿalu 'he is doing'
• passiveفُعِلَfuʿila 'it was done',يُفْعَلُyufʿalu 'it is being done'

Thus, the active and passive forms are spelled identically in Arabic; only their vowel markings differ. There are some exceptions to this in the case of weak roots.

Every verb has a corresponding activeparticiple, and most have passive participles. E.g.معلمmuʿallim 'teacher' is the active participle to stem II. of the rootع-ل-مʿ-l-m ('know').

• The active participle to Stem I isفاعلfāʿil, and the passive participle isمفعولmafʿūl.
• Stems II–X take prefixمـmu- and nominal endings for both the participles, active and passive. The difference between the two participles is only in the vowel between the last two root letters, which is-i- for active and-a- for passive (e.g. II. activeمفعِّلmu-faʿʿil, and passiveمفعَّلmu-faʿʿal).

In addition to a participle, there is averbal noun (in Arabic,مَصْدَرmaṣdar,pl.مَصَادِرmaṣādir, literally meaning 'source'), sometimes called a gerund, which is similar toEnglish gerunds and verb-derived nouns of various sorts (e.g. "running" and "a run" from "to run"; "objection" from "to object"). As shown by the English examples, its meaning refers both to the act of doing something and (by frequent semantic extension) to its result. One of its syntactic functions is as a verbal complement of another verb, and this usage it corresponds to the English gerund or infinitive (He prevented me fromrunning orHe beganto run).

• verbal noun formation to stem I is irregular.
• the verbal noun to stem II isتفعيلtafʿīl. For example:تحضيرtaḥḍīr 'preparation' is the verbal noun to stem II. of ح-ض-رḥ-ḍ-r ('to be present').
• stem III often forms its verbal noun with the feminine form of the passive participle, so forساعدsāʿada, 'he helped', produces the verbal nounمساعدةmusāʿadah. There are also some verbal nouns of the formفعالfiʿāl:جاهدjāhada, 'he strove', yieldsjihādجهاد 'striving' (for a cause or purpose).

Some well-known examples of verbal nouns areفتحfatḥ (seeFatah) (Form I),تنظيمtanẓīm (Form II),جهادjihād (Form III),إسلامislām (Form IV),انتفاضةintifāḍah (feminine of Form VIII verbal noun), andاستقلالistiqlāl (Form X).

The system ofverb conjugations in Arabic is quite complicated, and is formed along two axes. One axis, known as theform (described as "Form I", "Form II", etc.), is used to specify grammatical concepts such ascausative,intensive,reciprocal,passive orreflexive, and involves varying the stem form. The other axis, known as theweakness, is determined by the particular consonants making up the root. For example,defective (orthird-weak or final-weak) verbs have aوw orيy as the last root consonant (e.g.ر-م-يr-m-y 'throw',د-ع-وd-ʿ-w 'call'), anddoubled (or geminated) verbs have the second and third consonants the same (e.g.م-د-دm-d-d 'extend'). These "weaknesses" have the effect of inducing various irregularities in the stems and endings of the associated verbs.

Examples of the different forms of a sound verb (i.e. with no root weaknesses), from the rootك-ت-بk-t-b 'write' (usingح-م-رḥ-m-r 'red' for Form IX, which is limited to colors and physical defects):

The main types of weakness are as follows:

In Arabic thegrammatical person andnumber as well as themood are designated by a variety of prefixes and suffixes. The following table shows the paradigm of a regular sound Form I verb,kataba (كتب) 'to write'. Most of the final short vowels are often omitted in speech, except the vowel of the feminine plural ending-na, and normally the vowel of the past tense second person feminine singular ending-ti.

The initial vowel in the imperative (which is elidable) varies from verb to verb, as follows:

• The initial vowel isu if the stem begins with two consonants and the next vowel isu orū.
• The initial vowel isi if the stem begins with two consonants and the next vowel is anything else.
• There is no initial vowel if the stem begins with one consonant.

In unvocalised Arabic,katabtu,katabta,katabti andkatabat are all written the same:كتبت. Formskatabtu andkatabta (and sometimes evenkatabti) can be abbreviated tokatabt in spoken Arabic and in pausa, making them also sound the same.

ا (alif) in finalـُوا (-ū) is silent.

Roots containing one or two of the radicalsوw (wāw),يy (yāʾ ) orءʾ (hamzah) often lead to verbs with special phonological rules because these radicals can be influenced by their surroundings. Such verbs are called "weak" (verba infirma, 'weak verbs') and their paradigms must be given special attention. In the case ofhamzah, these peculiarities are mainly orthographical, sincehamzah is not subject to elision (the orthography ofءhamzah andاalif is unsystematic because Classical Arabic is a hybrid of Old Hejazi, the dialect in which the consonantal text was written down by the Prophet, with other dialects which showed phonetic and morphological differences).^[3] According to the position of the weak radical in the root, the root can be classified into four classes:first weak,second weak,third weak (or final weak) anddoubled, where both the second and third radicals are identical. Some roots fall into more than one category at once.

Most first-weak verbs have aوw as their first radical. These verbs are entirely regular in the past tense. In the non-past, thew drops out, leading to a shorter stem (e.g.,(يَجِدُ) وَجَدَwajada (yajidu) 'to find'), where the stem isـجِدـ-jid- in place of a longer stem likeـجْلِدـ-jlid- from the verbجَلَدَ (يَجْلِدُ)jalada (yajlidu) 'to whip, flog'. This same stem is used throughout, and there are no other irregularities except for the imperative, which has no initial vowel, consistent with the fact that the stem for the imperative begins with only one consonant.

There are various types of assimilated (first-weak) Form I verbs:

The following shows a paradigm of a typical Form I hollow (second-weak) verbقَالَ (قُلْتُ، يَقُولُ)qāla (qultu, yaqūlu) (root:ق-و-لq-w-l) 'to say', parallel to verbs of theفَعَلَ (يَفْعُلُ)faʿala (yafʿulu) type. See notes following the table for explanation.

All hollow (second-weak) verbs are conjugated in a parallel fashion. The endings are identical to those of strong verbs, but there are two stems (a longer and a shorter) in each of the past and non-past. The longer stem is consistently used whenever the ending begins with a vowel, and the shorter stem is used in all other circumstances. The longer stems end in a long vowel plus consonant, while the shorter stems end in a short vowel plus consonant. The shorter stem is formed simply by shortening the vowel of the long stem inall paradigms other than the active past of Form I verbs. In the active past paradigms of Form I, however, the longer stem always has anā vowel, while the shorter stem has a vowelu ori corresponding to the actual second root consonant of the verb.

No initial vowel is needed in the imperative forms because the non-past stem does not begin with two consonants.

There are various types of Form I hollow verbs:

• قَالَ، قُلْنَ (يَقُولُ، يَقُلْنَ) (root:ق-و-ل)qāla, qulna (yaqūlu, yaqulna) 'to say', formed from verbs withوw as their second root consonant and parallel to verbs of theفَعَلَ (يَفْعُلُ)faʿala (yafʿulu) type
• سَارَ، سِرْنَ (يَسِيرُ، يَسِرْنَ) (root:س-ي-ر)sāra, sirna (yasīru, yasirna) 'to get going, to travel', formed from verbs withيy as their second root consonant and parallel to verbs of theفَعَلَ (يَفْعِلُ)faʿala (yafʿilu) type
• خَافَ، خُفْنَ (يَخَافُ، يَخَفْنَ) (root:خ-و-ف)khāfa khufna (yakhāfu yakhafna) 'to fear', formed from verbs withوw as their second root consonant and parallel to verbs of theفَعِلَ (يَفْعَلُ)faʿila (yafʿalu) type
• نَامَ، نِمْنَ (يَنَامُ، يَنَمْنَ) (root:ن-ي-م)nāma, nimna (yanāmu, yanamna) 'to sleep', formed from verbs withيy as their second root consonant and parallel to verbs of theفَعِلَ (يَفْعَلُ)faʿila (yafʿalu) type

The passive paradigm of all Form I hollow verbs is as follows:

• قِيلَ، قِلْنَ (يُقَالُ، يُقَلْنَ)qīla qilna (yuqālu yuqalna) 'to be said'

The following shows a paradigm of a typical Form I defective (third-weak) verbرَمَى (يَرْمِي)ramā (yarmī) (root:ر-م-يr-m-y) 'to throw', parallel to verbs of theفَعَلَ (يَفْعِلُ)faʿala (yafʿilu) type. See notes following the table for explanation.

Two stems each

Each of the two main stems (past and non-past) comes in two variants, a full and a shortened. For the past stem, the full isرَمَيـramay-, shortened toرَمـram- in much of the third person (i.e. before vowels, in most cases). For the non-past stem, the full isrmiy-, shortened torm- before-ū -ī. The full non-past stemرْمِيْـrmiy- appears asرْمِيـrmī- when not before a vowel; this is an automatic alternation in Classical Arabic. The places where the shortened stems occur are indicated by silver (past), gold (non-past).

Irregular endings

The endings are actually mostly regular. But some endings are irregular, in boldface:

• Some of the third-person past endings are irregular, in particular those inرَمَىram-ā 'he threw',رَمَوْا⁩ram-aw 'they (masc.) threw'. These simply have to be memorized.
• Two kinds of non-past endings are irregular, both in the "suffixless" parts of the paradigm (largely referring to singular masculine or singular combined-gender). In the indicative, the full stemـرْمِي-rmī actually appears normally; what is irregular is the lack of the-u normally marking the indicative. In the jussive, on the other hand, the stem actually assumes a unique shortened formـرْمِـ-rmi, with a short vowel that is not represented by a letter in the Arabic.

The following shows a paradigm of a typical Form I defective (third-weak) verbدَعَا (يَدْعُو) (root:د-ع-و)daʿā (yadʿū) 'to call', parallel to verbs of theفَعَلَ (يَفْعُلُ)faʿala (yafʿulu) type. Verbs of this sort are entirely parallel to verbs of theفَعَا (يَفْعِي)faʿā (yafʿī) type, although the exact forms can still be tricky. See notes following the table for explanation.

Verbs of this sort are work nearly identically to verbs of theفَعَى (يَفْعِي)faʿā (yafʿī) type. There are the same irregular endings in the same places, and again two stems in each of the past and non-past tenses, with the same stems used in the same places:

• In the past, the full stem isدَعَوـdaʿaw-, shortened toدَعـdaʿ-.
• In the non-past, the full stem isدْعُوْـdʿuw-, rendered asدْعُوـdʿū- when not before a vowel and shortened toدْعـdʿ- beforeـُو، ـِي-ū, -ī.

The Arabic spelling has the following rules:

• In the third person masculine singular past, regularاʾalif appears instead ofىʾalif maqṣūrah: henceدَعَا, not *دَعَى.
• The otiose finalalif appears only after the finalwāw of the plural, not elsewhere: henceتَدْعُو 'you (mascsg) call (ind)' butتَدْعُوا 'you (mascpl) call (sjv)', even though they are both pronouncedتَدْعُوtadʿū.

The following shows a paradigm of a typical Form I defective (third-weak) verbنَسِيَ (يَنْسَ)nasiya (yansā) (root:ن-س-ي) 'to forget', parallel to verbs of theفَعِلَ (يَفْعَلُ)faʿila (yafʿalu) type. These verbs differ in a number of significant respects from either of the above types.

Multiple stems

This variant is somewhat different from the variants withـِي-ī orـُو-ū in the non-past. As with other third-weak verbs, there are multiple stems in each of the past and non-past, a full stem composed following the normal rules and one or more shortened stems.

• In this case, only one form in the past uses a shortened stem:نَسُوnas-ū 'they (masc) forgot'. All other forms are constructed regularly, using the full stemنَسِيْـnasiy- or its automatic pre-consonant variantنَسِيـnasī-.
• In the non-past, however, there are at least three different stems:

1. The full stemـنْسَيـ-nsay- occurs beforeـَ/ـَى-a/ā- orـنـ-n-, that is before dual endings, feminine plural endings and energetic endings corresponding to forms that are endingless in the jussive.
2. The modified stemـنْسَى-nsā occurs in "endingless" forms (i.e. masculine or common-gender singular, plus 1st plural). As usual with third-weak verbs, it is shortened toـنْسَ-nsa in the jussive. These forms are marked with red.
3. Before endings normally beginning withـِ/ـِي-i/ī- orـُ/ـُو-u/ū-, the stem and endings combine into a shortened form: e.g. expected*تَنْسَيِينَ*ta-nsay-īna 'you (femsg) forget',*تَنْسَيُونَ*ta-nsay-ūna 'you (mascpl) forget' instead becomeتَنْسَيْنَta-nsayna,تَنْسَوْنَta-nsawna respectively. The table above chooses to segment them asتَنْسَيْنَta-nsa-yna,تَنْسَوْنَta-nsa-wna, suggesting that a shortened stemـنْسَـ-nsa- combines with irregular (compressed) endingsـيْنَ-yna <*ـِينَ*-īna,ـوْنَ-wna <ـُونَ*-ūna. Similarly subjunctive/jussiveتَسنَوْاta-nsaw <تَسنَيُوْا*ta-nsay-ū; but note energeticتَنْسَوُنَّta-nsawunna <تَنْسَيُنَّ*ta-nsay-unna, where the originalـيُـ*-yu- has assimilated toـوُـ-wu-. Consistent with the above analysis, we analyze this form asتَنْسَوُنَّta-nsa-wunna, with an irregular energetic endingـوُنَّ-wunna where aglide consonant has developed after the previous vowel. However, since all moods in this case have a form containingـنْسَوـ-nsaw-, an alternative analysis would considerـنْسَوـ-nsaw andـنْسَيـ-nsay as stems. These forms are marked with gold.

Irregular endings

The endings are actually mostly regular. But some endings are irregular in the non-past, in boldface:

• The non-past endings in the "suffixless" parts of the paradigm (largely referring to singular masculine or singular combined-gender). In the indicative and subjunctive, the modified stemـنسَاـ-nsā appears, and is shortened toـنسَـ-nsa in the jussive. In the forms actually appears normally; what is irregular is the lack of theـُ-u normally marking the indicative. In the jussive, on the other hand, the stem actually assumes a unique shortened formـنْسَـ-nsa, with a short vowel that is not represented by a letter in the Arabic script.
• In the forms that would normally have suffixesـِ/ـِي-i/ī- orـُ/ـُو-u/ū-, the stem and suffix combine to produceـنْسَيـ-nsay-,ـنْسَوـ-nsaw-. These are analyzed here as consisting of a shortened stem formـنْسَـ-nsa- plus irregular (shortened or assimilated) endings.

The following shows a paradigm of a typical Form I doubled verbمَدَّ (يَمُدُّ) (root:م-د-د)madda (yamuddu) 'to extend', parallel to verbs of theفَعَلَ (يَفْعُلُ)faʿala (yafʿulu) type. See notes following the table for explanation.

All doubled verbs are conjugated in a parallel fashion. The endings are for the most part identical to those of strong verbs, but there are two stems (a regular and a modified) in each of the past and non-past. The regular stems are identical to the stem forms of sound verbs, while the modified stems have the two identical consonants pulled together into ageminate consonant and the vowel between moved before the geminate. In the above verbمَدَّ (يَمُدُّ)madda (yamuddu) 'to extend (s.th.)', the past stems areمَدَدـmadad- (regular),مَدّـmadd- (modified), and the non-past stems areمْدُدـmdud- (regular),مُدّـmudd- (modified). In the table, places where the regular past stem occurs are in silver, and places where the regular non-past stem occurs are in gold; everywhere else, the modified stem occurs.

No initial vowel is needed in most of the imperative forms because the modified non-past stem does not begin with two consonants.

The concept of having two stems for each tense, one for endings beginning with vowels and one for other endings, occurs throughout the different kinds of weaknesses.

Following the above rules, endingless jussives would have a form likeتَمْدُدtamdud, while the corresponding indicatives and subjunctives would have forms likeتَمُدُّtamuddu,تَمُدَّtamudda. As a result, for the doubled verbs in particular, there is a tendency to harmonize these forms by adding a vowel to the jussives, usuallyـَa, sometimesـِi. These are the only irregular endings in these paradigms, and have been indicated in boldface. The masculine singular imperative likewise has multiple forms, based on the multiple forms of the jussive.

There are various types of doubled Form I verbs:

Arabic verb morphology includesaugmentations of the root, also known asforms, an example of thederived stems found among the Semitic languages. For a typical verb based on atriliteral root (i.e. a root formed using three root consonants), the basic form is termedForm I, while the augmented forms are known asForm II,Form III, etc. The forms in normal use are Form I through Form X; Forms XI through XV exist but are rare and obsolescent. Forms IX and XI are used only with adjectival roots referring to colors and physical defects (e.g. "red", "blue", "blind", "deaf", etc.), and arestative verbs having the meaning of "be X" or "become X" (e.g. Form IXiḥmarra 'be red, become red, blush', Form XIiḥmārra with the same meaning). Although thestructure that a given root assumes in a particular augmentation is predictable, itsmeaning is not (although many augmentations have one or more "usual" or prototypical meanings associated with them), and not all augmentations exist for any given root. As a result, these augmentations are part of the system ofderivational morphology, not part of the inflectional system.

The construction of a given augmentation is normally indicated using the dummy rootf–ʿ–l (ف–ع–ل), based on the verbfaʿala 'to do'. Because Arabic has no direct equivalent to theinfinitive form of Western languages, the third-person masculine singular past tense is normally used as thedictionary form of a given verb, i.e. the form by which a verb is identified in a dictionary or grammatical discussion. Hence, the wordfaʿala above actually has the meaning of 'he did', but is translated as 'to do' when used as a dictionary form.

Verbs based onquadriliteral roots (roots with four consonants) also exist. There are four augmentations for such verbs, known as Forms Iq, IIq, IIIq and IVq. These have forms similar to Forms II, V, VII and IX respectively of triliteral verbs. Forms IIIq and IVq are fairly rare. The construction of such verbs is typically given using the dummy verbfaʿlala (root: ف-ع-ل-ل). However, the choice of this particular verb is somewhat non-ideal in that the third and fourth consonants of an actual verb are typically not the same, despite the same consonant used for both; this is a particular problem e.g. for Form IVq. The verb tables below use the dummy verbfaʿlaqa (root: ف-ع-ل-ق) instead.

Some grammars, especially of colloquial spoken varieties rather than of Classical Arabic, use other dummy roots. For example,A Short Reference Grammar of Iraqi Arabic (Wallace M. Erwin) uses فملFaMaLa (root: ف-م-ل) and فستلFaSTaLa (root: ف-س-ت-ل) for three and four-character roots, respectively (standing for "First Middle Last" and "First Second Third Last"). Commonly the dummy consonants are given in capital letters.

The system of identifying verb augmentations byRoman numerals is an invention by Western scholars. Traditionally, Arabic grammarians did not number the augmentations at all, instead identifying them by the corresponding dictionary form. For example, Form V would be called "thetafaʿʿala form".

Each form can have either active or passive forms in the past and non-past tenses, so reflexives are different from passives.

Note that the present passive of forms I and IV are the same. Otherwise there is no confusion.

Sound verbs are those verbs with no associated irregularities in their constructions. Verbs with irregularities are known asweak verbs; generally, this occurs either with (1) verbs based on roots where one or more of the consonants (orradicals) isw (wāw, و),y (yāʾ, ي) or theglottal stopʾ (hamzah, ﺀ); or (2) verbs where the second and third root consonants are the same.

Some verbs that would be classified as "weak" according to the consonants of the verb root are nevertheless conjugated as a strong verb. This happens, for example:

• Largely, to all verbs whose only weakness is a hamzah radical; the irregularity is in the Arabic spelling but not the pronunciation, except in a few minor cases.
• Largely, to all verbs whose only weakness is ay in the first radical (the "assimilated" type).
• To all verbs conjugated in Forms II, III, V, VI whose only weakness is a وw or يy in the first or second radicals (or both).

Form VIII has a ـتـ -t- that isinfixed into the root, directly after the first root consonant. This ـتـ -t-assimilates to certaincoronal consonants occurring as the first root consonant. In particular, with roots whose first consonant is د، ز، ث، ذ، ص، ط، ض، ظd z th dh ṣ ṭ ḍ ẓ, the combination of root and infix تt appears as دّ، زد، ثّ، ذّ، صط، طّ، ضط، ظّdd zd thth dhdh ṣṭ ṭṭ ḍṭ ẓẓ. That is, thet assimilates the emphasis of theemphatic consonants ص، ط، ض، ظṣ ṭ ḍ ẓ and thevoicing of د، زd z, and assimilates entirely to theinterdental consonants ث، ذ، ظth dh ẓ. The consonant cluster ضطḍṭ, as in اضطرّiḍṭarra 'compel, force', is unexpected given modern pronunciation, having a voiced stop next to a voiceless one; this reflects the fact that طṭ was formerly pronounced voiced, and ضḍ was pronounced as the emphatic equivalent not of دd but of an unusuallateral sound. (ضḍ was possibly an emphaticvoiced alveolar lateral fricative/ɮˤ/ or a similaraffricated sound/dɮˤ/ or/dˡˤ/; see the article on the letter ضḍād.)

Other than for Form I active, there is only one possible form for each verb, regardless of whether the third root consonant is وw or يy. All of the derived third-weak verbs have the same active-voice endings as (فعى (يفعيfaʿā (yafʿī) verbs except for Forms V and VI, which have past-tense endings like (فعى (يفعيfaʿā (yafʿī) verbs but non-past endings like (فعي (يفعىfaʿiya (yafʿā) verbs. The passive-voice endings of all third-weak verbs (whether Form I or derived) are the same as for the (فعي (يفعىfaʿiya (yafʿā) verbs. The verbal nouns have various irregularities: feminine in Form II,-in declension in Form V and VI, glottal stop in place of rootw/y in Forms VII–X.

The active and passive participles of derived defective verbs consistently are of the-in and-an declensions, respectively.

Defective Form IX verbs are extremely rare. Heywood and Nahmad list one such verb,iʿmāya 'be/become blind', which does not follow the expected form اعميّ*iʿmayya.^[4] They also list a similarly rare Form XI verb اعمايّiʿmāyya 'be/become blind' — this time with the expected form.

Only the forms with irregularities are shown. The missing forms are entirely regular, withw ory appearing as the second radical, depending on the root. There are unexpected feminine forms of the verbal nouns of Form IV, X.

When the first radical isw, it drops out in the Form I non-past. Most of the derived forms are regular, except that the sequencesuw iw are assimilated toū ī, and the sequencewt in Form VIII is assimilated tott throughout the paradigm. The following table only shows forms with irregularities in them.

The initialw also drops out in the common Form I verbal noun علةʿilah (e.g. صلةṣilah 'arrival, link' from وصلةwaṣalah 'arrive').Root: و-ع-ل

When the first radical isy, the forms are largely regular. The following table only shows forms that have some irregularities in them, indicated inboldface.Root: ي-ع-ل

Root: ف-ل-ل

The largest problem with so-called "hamzated" verbs (those with a glottal stopʾ or "hamzah" as any of the root consonants) is the complicated way of writing such verbs in the Arabic script (see the article onhamzah for the rules regarding this). In pronunciation, these verbs are in fact almost entirely regular.

The only irregularity occurs in verbs with a hamzah ء as the first radical. A phonological rule in Classical Arabic disallows the occurrence of two hamzahs in a row separated by a short vowel, assimilating the second to the preceding vowel (henceʾaʾ ʾiʾ ʾuʾ becomeʾā ʾī ʾū). This affects the following forms:

• The first-person singular of the non-past of Forms I, IV and VIII.
• The entire past and imperative of Form IV.

In addition, any place where ahamzat al-waṣl (elidable hamzah) occurs willoptionally undergo this transformation. This affects the following forms:

• The entire imperative of Form I.
• The entire past and imperative of Form VIII, as well as the verbal noun of Form VIII.

There are the following irregularities:

• The common verbsʾakala (أكل; root: ء-ك-ل) 'eat',ʾakhadha (أخذ; root: ء-خ-ذ) 'take',ʾamara (أمر; root: ء-م-ر) 'command' have irregular, short imperativeskul, khudh, mur.
• Form VIII of the common verbʾakhadha 'take' isittakhadha 'take on, assume', with irregular assimilation of the hamzah.
• The common verbsaʾala yasʾalu 'ask' has an alternative non-pastyasalu with missing hamzah.

Doubly weak verbs have two "weak" radicals; a few verbs are also triply weak. Generally, the above rules for weak verbs apply in combination, as long as they do not conflict. The following are cases where two types of weaknesses apply in combination:

• Verbs with aw in the first radical and aw ory in the third radical. These decline as defective (third-weak) verbs, andalso undergo the loss ofw in the non-past of Form I, e.g.waqā yaqī 'guard',wafā yafī 'complete, fulfill (a promise)',waliya yalī 'be near, follow'. These verbs have extremely short imperativesqi fi li (feminineqī fī lī, masculine pluralqū fū lū, feminine pluraliqna ifna ilna), although these are not normally used inModern Standard Arabic. Similarly, verbs of this sort in Form IV and Form VIII are declined as defective but also have the normal assimilations ofw-initial verbs, e.g. Form IVawfā yūfī 'fulfill a vow', Form VIIIittaqā yattaqī 'fear (God)', augmentations ofwafā yafī andwaqā yaqī, respectively (see above).
• Verbs with a hamzah in the first radical and aw ory in the third radical. These decline as defective (third-weak) verbs, andalso undergo the assimilations associated with the initial hamzah, e.g. the common verbʾatā yaʾtī 'come' (first singular non-pastʾātī 'I come') and the related Form IV verbʾātā yuʾtī 'bring' (first singular non-pastʾūtī 'I bring').

The following are examples where weaknesses would conflict, and hence one of the "weak" radicals is treated as strong:

• Verbs with aw ory in both the second and third radicals. These are fairly common, e.g.rawā yarwī 'recount, transmit'. These decline as regular defective (third-weak) verbs; the second radical is treated as non-weak.
• Verbs with aw in the first radical and the second and third radicals the same. These verbs donot undergo any assimilations associated with the first radical, e.g.wadda (wadidtu) yawaddu 'to love'.
• Verbs with a hamza in the first radical and the second and third radicals the same. These verbs donot undergo any assimilations associated with the first radical, e.g.ʾajja yaʾujju 'burn', first singular non-pastʾaʾujju 'I burn', despite the two hamzahs in a row.

The following are cases with special irregularities:

• Verbs with aw ory in the second radical and a hamzah in the third radical. These are fairly common, e.g. the extremely common verbjāʾa yajīʾu 'come'. The only irregularity is the Form I active participle, e.g.jāʾin 'coming', which is irregularly declined as a defective (third-weak) participle (presumably to avoid a sequence of two hamzahs in a row, as the expected form would be*jāʾiʾ).
• The extremely common verbraʾā yarā 'see'. The hamzah drops out entirely in the non-past. Similarly in the passive,ruʾiya yurā 'be seen'. The active participle is regularrāʾin and the passive participle is regularmarʾīy-. The related Form IV verbarā yūrī 'show' is missing the hamzah throughout. Other augmentations are regular: Form IIIrāʾā yurāʾī 'dissemble', Form VItarāʾā yatarāʾā 'look at one another', Form VIIIirtaʾā yartaʾī 'think'.
• The common verbḥayiya yaḥyā 'live', with an alternative past tenseḥayya. Form IVaḥyā yuḥyī 'resuscitate, revive' is regular. Form Xistaḥyā yastaḥyī 'spare alive, feel ashamed' also appears asistaḥayya andistaḥā.

The vowels for the various forms are summarized in this table: