Allomorph

What is an allomorph?

An allomorph is one of two or more complementary morphs which manifest a morpheme in its different phonological or morphological environments.

Morpheme in english which indicatesplurality or third person singular present tense has three allomorps:

Example

         Cat(s)   / kaets/               dog(s)/dogz/                horses(s) /ho:sez/

        Like(s) /laiks/                   rubs/rᴧbz/                    hiss(es) /hisez/

English has several morphemes that vary in sound but not in meaning. Examples include the past tense and the plural morphemes.

For example, in English, a past tense morpheme is -ed. It occurs in several allomorphs depending on its phonological environment, assimilating voicing of the previous segment or inserting a schwa when following an alveolar stop:

• as /əd/ or /ɪd/ in verbs whose stem ends with the alveolar stops /t/ or /d/, such as 'hunted' /hʌntɪd/ or 'banded' /bændɪd/
• as /t/ in verbs whose stem ends with voiceless phonemes other than /t/, such as 'fished' /fɪʃt/
• as /d/ in verbs whose stem ends with voiced phonemes other than /d/, such as 'buzzed' /bʌzd/

References

https://en.wikipedia.org/wiki/Allomorph

http://www-01.sil.org/linguistics/GlossaryOfLinguisticTerms/WhatIsAnAllomorph.htm