InCantonese phonology, a close relationship exists between thenasal codas (-m,-n,-ŋ) and thestopcodas (-p,-t,-k). These two types of codas can also be classified into threehomorganic pairs: the bilabialm/p, the dentaln/t, and the velarŋ/k. Some of the correspondences trace back toOld Chinese, or developed as a historical coincidence of sound change. However, many pairs exist that are solely Cantonese and not found in Classical Chinese.

Apart from phonetical association, the homorganic pairs are also semantically related. For some characters (or words) with syllables ending in nasals, there aresemantically similar characters which have the homorganic stops. For example, bothdam3揼 anddap1耷 means 'to hang down'. The initial consonants and the vowels of the alternating pair are identical while the terminal nasal/-m/ and stop/-p/ are a homorganic pair. In Cantonese phonology, this interesting phenomenon is known as nasal-stop alternation (陽入對轉), mainly an alternation of homorganic consonants between nasal and stop finals. In otherdialects, it could beoral-nasal or oral-stop alternation.

Regarding the initial consonants, a few items may alternate between aspirated and unaspirated initial stops, e.g.kim4拑 'to pinch' andgip6挟 'to squeeze together'. As for tones, high or low tones on syllables with nasal codas usually (but not always) correspond to high or low tones on syllables with stop codas, e.g.ngam4吟 'to grumble' has a low tone whereasngap1噏 'to babble' has a high tone.

Many of these characters arecolloquial verbs which lack standardChinese characters as their written forms. For example, there is not a widely accepted character forjip3 'to pickle in salt'. Consequently, the homorganic characterjim1腌 is also used to represent both syllables.^[1] The same is true fordoek3啄 'to peck' being used to stand fordoeng1 as well.

As for their semantics or usage, the paired characters are not completely equivalent or interchangeable in every case. The colloquial verbkam2冚 seems to be more commonly used than the correspondingkap1扱, both meaning 'to cover on top'. On the other hand,fing6捹 andfik6扐 both mean 'to throw away; to swing an object in the hand' and are interchangeable; the same is also true forning1拎 andnik1搦 'to carry in the hand'.

Mostlinguists believe that the syllables with nasal codas are the more basic originals while the stops are the colloquial variants.^[2] A few opine that there are an equal number of word pairings that are originated from the syllables with stop codas.^[3] However, it is generally agreed that the usage of the nasal members are less restricted than their stop counterparts.

Other linguists regard the alternation between homorganic final consonants in pairs of semantically-related words as a feature widely found among languages ofSoutheast Asia as well as south China (Chuang-chia andHmong for example). Such paired words belong to a "word-family", a term first used by Bernhard Karlgren (1934) to refer to sets of words with similar (but not identical) sound inArchaic Chinese that were related in meaning, representing relics of morphological processes.^[4] Similarly, Bauer notes that the Cantonese phenomenon is believed to be a remnant of an ancient word-derivation process, now no longer productive, in which different types of suffixes (causative and transitive) were attached to lexical roots.^[5]

In the Cantonese syllabary, there are about 50 pairs of such characters that show alternation between homorganic nasal and stop codas. The following is a list of some examples for reference:

• Modern Cantonese Phonology by Robert S. Bauer and Paul K. Benedict (Ohio State University)
• Homorganic Nasal/Stop Alterations in Cantonese by Benjamin K. T'sou (University of Hong Kong)

• Cantonese phonology
• Cantonese language

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