An allomorph is one of two or more complementary morphs which manifest a morpheme in its different phonological or morphological environments.
The allomorphs of a morpheme are derived from phonological rules and any morphophonemic rules that may apply to that morpheme.
The plural morpheme in English, usually written as '-s', has at least three allomorphs:
• [-s] as in [hQts] 'hats'
• [-z] as in [d&u0254;gz] 'dogs'
• [«z] as in [bŒks«z] 'boxes'