Finnish has a system ofpossessive suffixes, which are used in addition to or instead of the genitive case to express possession when the possessor is expressed with a personal pronoun. There are five distinct suffixes, depending on the person that is acting as the possessor (note that the third-person singular and third-person plural are not distinguished):
| possessor | singular | plural |
|---|---|---|
| 1st person | -ni(“my”) | -mme(“our”) |
| 2nd person | -si(“your (sg)”) | -nne(“your (pl)”)* |
| 3rd person | -nsa,-nsä(“his, her, their”) (-an,-än,-en) | |
| *)Also the polite form | ||
The suffix attaches to the end of the word, but assimilates a final-n in the genitive and illative forms.
The first-person and second-person suffixes can be used not just alongside, but in place of the pronoun, which can be omitted if a possessive suffix is present; thustaloni andminuntaloni are synonymous. The case for the third-person suffix is different: if used on its own, it has a reflexive meaning, and because of this, the third-person pronoun cannot be left out in the same way as the first- and second-person ones can:
There are no separate nominative forms for inflected words; both the nominative singular and plural have identical forms to the genitive singular, if a possessive suffix is present. The suffixes themselves make no distinction for the number of the possessed, but can be attached to inflected forms; that is, words can be inflected even if they have a possessive suffix.
The third-person possessive suffix also has a short form-Vn (V represents the previous vowel that is made long), which can only be used after the short vowelsa,ä,e, and may not be used in the nominative or genitive cases.
| Can the nominal form take the short third-person possessive suffix? | ||
|---|---|---|
| case | singular | plural |
| nominative |  No | No |
| genitive | No | No |
| partitive | Possibly* |  Yes |
| accusative | No | No |
| inessive | Yes | Yes |
| elative | Yes | Yes |
| illative | No | No |
| adessive | Yes | Yes |
| ablative | Yes | Yes |
| allative | Yes | Yes |
| essive | Yes | Yes |
| translative | Yes | Yes |
| abessive | Yes | Yes |
| instructive | — | No |
| comitative | — | Yes |
| *) If the partitive form does not end in-aa or-ää. | ||
When the short suffix can be used, it usually is.
The first-person singular possessive suffix has an alternative version,-in, which is poetic and thus chiefly used in poetry and music (however, its use is restricted; see the entry for more).
In colloquial Finnish, possessive suffixes are much less common.
Possessive suffixes will usually not be used with nominals, and the possessive structure instead uses the personal pronoun in the genitive case (which is subsequently never omitted). The same applies to e.g. postpositions and infinitive/participle forms. The comitative suffix, which requires a possessive suffix, is rarely used in colloquial speech anyway.
The second-person singular suffix-s(i) is occasionally used in colloquial Finnish, however, especially when used emphatically.
Predicative adverbials are generally less common, but when used, the possessive suffix is still used with them, even in colloquial Finnish. However, for some speakers, the third-person form may be used in all cases, which is grammatically incorrect in standard Finnish.
In addition, the possessive ending in the reflexive pronounitsensä is still used in colloquial Finnish.
Possessive suffixes are not used (except for the reflexive usage of the third-person possessive suffix) if the complement in the genitive case isnot a pronoun (such as if it is a name).
Most nouns can receive a possessive suffix.
In addition, the comitative case requires a possessive suffix for nouns (but not adjectives).
Adjectives usually do not receive a possessive suffix, even when used with a noun that has a possessive suffix. Thus, as an example, ×keltaiseni autoni is wrong, and should instead bekeltainenautoni.
However, if the adjective is used beingsubstantively, i.e. without a modifying noun, it may receive a possessive suffix.
In addition, adjectives used for comparisons of equality (such asikäinen(“of ... age, as old as”),pituinen(“of ... length, as long as”) etc.) can receive a possessive suffix (such asikäiseni(“of my age, the same age as me, as old as me”)). In this case, the modified noun does not automatically receive a possessive suffix.
Some adverbs receive a possessive suffix, and out of those most require it. The adverbs that require a possessive suffix are referred to aspredicative adverbials (list).
Certain postpositions, such askanssa orluona, can also receive a possessive suffix. It is usually required when the complement is a personal pronoun (although it is optional for some postpositions):
No possessive suffix is used when the complement is not a pronoun:
(Cardinal) numerals cannot receive a possessive suffix.
In some verb phrases, the object or some other word may receive a possessive suffix. There are two main types:
Agent participles require either a possessive suffix or a subject in the genitive case. For other types of participles, possessive suffixes are used as for adjectives.
Some verb forms, including participles, have special uses for possessive suffixes: