Morphemes

A morpheme is the smallest unit of meaning or grammatical function in a language. It is the minimal unit that cannot be further divided without losing its contribution to meaning. Morphemes may be free, meaning they can stand alone (for example cat, run), or bound, meaning they must attach to another element (for example -s for plural, un- as a prefix).

Free morphemes are typically roots. Bound morphemes include affixes such as prefixes and suffixes. In cats, cat is a free morpheme and -s is a bound morpheme indicating plural. In happiness, happy is free and -ness is bound; in unbelievable, un- is bound, believe is free, -able is bound.

Morphology distinguishes inflectional morphemes, which express grammatical information without changing word class (such as -s for plural, -ed for past tense), from derivational morphemes, which create new words or alter word class (such as -ness, -ful, re-). Morphemes can show allomorphy, changing phonological form according to context (for example the plural forms [s], [z], and [ɪz]).

In some languages, morphemes are used more systematically than in others. Isolating languages rely mainly on free morphemes; agglutinative languages attach many clear affixes; fusional languages combine several grammatical meanings in a single affix. Suppletion also demonstrates morphemic irregularity, as in went from go.

Linguists analyze words by segmenting them into morphemes, a practice central to lexicography, language teaching, and natural language processing. Studying morphemes helps explain how meaning is built, how grammar operates, and why languages differ in their word-formation strategies.