morphèmes

A morpheme is the smallest unit of language that carries meaning or a grammatical function. It cannot be further divided without altering the meaning or the grammatical role of the word it helps form. Morphemes are the building blocks of words and are studied in morphology, a field of linguistics.

Morphemes are classified as free or bound. Free morphemes can stand alone as words, such as cat or run. Bound morphemes must attach to another unit, such as the plural suffix -s or the past tense suffix -ed. They can be further categorized as lexical (content) morphemes, which carry semantic information like cat or stay, and grammatical (function) morphemes, which encode grammatical relations like the definite article the, or the suffix -ing.

Derivational morphemes create new words or change word class, as in teach vs teacher or happy vs happiness. Inflectional morphemes modify grammatical features without changing the core meaning or part of speech, such as number, tense, or case, as in cats, walked, or girls.

Morphemes can have different surface forms, a phenomenon known as allomorphy. For example, the plural morpheme in English is pronounced as /s/, /z/, or /ɪz/ depending on the final sound of the word. Some languages also employ zero morphemes, where no overt affix marks a grammatical property.

In analysis, words are decomposed into sequences of morphemes, revealing the morphology of a language. Different languages exhibit varying degrees of morphology, from isolating systems with few bound morphemes to highly agglutinative or fusional systems.