4.2 Morpheme: the minimal meaningful unit of language

　 Speakers of a language know how to break words into their components. English speakers know the word antidisestablishmentarianism can be broken into seven parts. Each part is meaningful, and each is a recurring form, that is, each of the seven parts is found in other English words. If any of them was further broken, it would be no longer meaningful. The smallest meaningful unit of language is called a morpheme.

　 A morpheme may be represented by different forms, called allomorphs. The English prefix {in-}, for example, has four allomorphs, as found in the words impossible, immoral, irregular, irresistible. The plural form of English countable nouns is also a morpheme which has allomorphs, namely, -s and –es. Some countable nouns do not change form to express plurality. In the phrases a herd of cattle, a flock of sheep, the head noun is plural in sense. In this case, both cattle and sheep contain two morphemes. Similarly, some regular verbs do not change form to indicate past tense. In the sentence, He cut his fingers in an accident, the verb contains two morphemes. The word went also contains two morphemes. Words like this, which is not related in form to indicate grammatical contrast with the root, are called suppletives.