lexèmes

In linguistics, a lexeme is the abstract unit of meaning that underlies a set of related word forms. It represents the core semantic content of a word, independent of its grammatical variants. For example, the lexeme be includes the surface forms be, am, is, are, was, were, being, been; the lexeme dog includes dog and dogs, and its possessive dog’s.

The term lemma is closely related and often used interchangeably, though usage varies. A lemma is typically the canonical dictionary form of a lexeme. A single lexeme can yield multiple inflected forms through morphology, while the lemma is the form used to represent the whole family of forms in a dictionary or linguistic analysis.

Lexemes can be single words or multiword expressions that behave as a unit in a language. Fixed phrases such as kick the bucket or by and large are often treated as lexical items whose meaning cannot be inferred from the individual words. Lexemes also cover polysemy and synonyms, with a single lexeme sometimes carrying several related meanings in different contexts.

In practice, the concept of a lexeme is central to lexicon-based analysis, lemmatization, and natural language processing. It helps distinguish the abstract semantic unit from its concrete surface realizations and supports tasks such as part-of-speech tagging, parsing, and semantic interpretation.