An allomorph is a variant form of a morpheme; it's spelt the same, but pronounced differently.

Allomorphs of Bound Morphemes

(I'm not certain, but I think allomorphs are mostly bound morphemes)

Examples are the inflectional suffix "-ed":

  • wanted = ud (the "u" is an indeterminate vowel sound)
  • pushed = t
  • died = d

Or the (also inflectional suffix) plural form:

  • -/s/ = after voiceless sounds (e.g. lifts)
  • -/z/ = after voiced sounds (e.g. trees)
  • -/…ôz/ = after /sibiliants/ (e.g. pushes)