An allomorph is a variant form of a morpheme. The concept of allomorphy arises in morphology, which is the study of the structure and formation of words. Allomorphs are essentially different “versions” of a single morpheme that manifest under specific conditions or in particular environments. These variants are often the result of phonological processes affected by the surrounding sounds.

Here are some key points and examples related to allomorphs:

Plural Allomorphs in English: The plural morpheme in English is usually represented as “-s”, but it has different phonetic realizations based on the ending sound of the noun it’s attached to:

  • [s] as in “cats”
  • [z] as in “dogs”
  • [ɪz] as in “horses” These three variants ([s], [z], [ɪz]) are allomorphs of the plural morpheme in English.

Past Tense Allomorphs in English: The regular past tense morpheme in English can also be realized in different ways:

  • [t] as in “worked”
  • [d] as in “played”
  • [ɪd] as in “wanted” Again, these are allomorphs of the regular past tense morpheme.

Prefix Allomorphs: The negative prefix “in-” in English has different forms based on the following sound:

  • “in-” as in “inactive”
  • “il-” as in “illegal”
  • “im-” as in “impossible”
  • “ir-” as in “irregular” These variants are allomorphs of the negative prefix.

Reasons for Allomorphy: Allomorphy can be due to:

  • Phonological conditions (e.g., based on surrounding sounds, as seen in the plural and past tense examples).
  • Morphological conditions (e.g., based on the type or class of morpheme it attaches to).
  • Lexical conditions (e.g., irregular forms that have to be memorized, such as “go” vs. “went”).

Underlying Representation: Often, one form (or allomorph) of a morpheme is considered the basic or default form, called the underlying representation. Phonological rules then dictate how this form changes in different environments to produce the various allomorphs.

Understanding allomorphy helps linguists and language learners recognize the variability and flexibility of language. It also sheds light on the interactions between morphology and phonology, showcasing how the structure of words and the sounds within them are interrelated.