lexicon

A lexicon is the collection of words and related lexical items that make up the vocabulary of a language or the vocabulary that an individual speaker knows. In linguistic usage, the term often refers to the mental lexicon, the internal repository of lexical entries that a speaker can draw on during comprehension and production. Each entry, a lexeme, encodes a word's core meaning and information about its form, pronunciation, part of speech, and syntactic behavior. Inflected forms and derived words are linked to the same underlying lemma within the lexicon.

The word lexicon derives from Latin lexicon, in turn from Greek lexis meaning "word" or "speech."

In practice, a lexicon includes not just form and meaning but also information about syntactic licensing, typical collocations, semantic relations (synonyms, antonyms, hyponyms), and variants such as inflections and derivations. It may also indicate frequency, register, and historical usage. Some entries include etymology and notes on sense distinctions.

Lexicography is the academic discipline of compiling dictionaries and other lexical resources. Dictionaries provide standardized spellings, definitions, pronunciation guides, parts of speech, example sentences, and often notes on usage and etymology. Historical dictionaries document how a language's lexicon has changed over time.

The lexicon is dynamic: new words are created or borrowed, meanings shift, and specialized vocabularies develop for emerging technologies. In cognitive science, the mental lexicon is examined as the organization of word knowledge in the mind. In computational linguistics, lexicons are structured databases of lemmas, senses, and relations that support parsing, sense disambiguation, and information retrieval; large resources such as WordNet exemplify this approach.