morfem

A morfem is the smallest unit of language that carries meaning or a grammatical function. It is the minimal unit of form-meaning that can combine with other morfems to build words. Morfems are abstract units: their pronunciation or spelling may vary across contexts, but their function remains constant. The study of morfems and their combinations is called morphology.

Types include free morfems, which can stand alone as words (for example 'cat', 'run'), and bound morfems, which must attach to a host (such as the plural suffix '-s' or the past tense '-ed'). Morfems are also classified by function: inflectional morfems add grammatical information without changing the word's category (e.g., -s for plural, -ed for past), while derivational morfems create new words or change category (e.g., prefix 'un-', suffix '-ness').

Allomorphy occurs when a single morfem has different phonetic realizations. For example, the plural morfem in English is realized as [s], [z], or [ɪz] depending on the surrounding sound. The underlying morfem remains the same even as its pronunciation changes.

An example is the word 'unbelievable', which can be segmented as un- + believe + -able. Here, un- is a bound derivational prefix, believe is a free morfem (root), and -able is a bound derivational suffix. English also uses irregular morphology, such as go → went, which shows that morfems participate in broader word-formation patterns.

Morfems are central to linguistics, language description, dictionary compilation, and natural language processing. They provide a framework for analyzing word formation, inflection, and cross-linguistic differences in morphology.