English from the 17th century, from a Medieval Latin or New Latin lexicon, from Ancient Greek λεξικόν (lexicon, “a lexicon”), neuter of λεξικός (lexikos, “of words”), from λέξις (lexis, “a saying, speech, word”), from λέγειν (legein, “to speak”).
- The vocabulary of a language.
- (linguistics) A dictionary that includes or focuses on lexemes.
- A dictionary of Classical Greek, Hebrew, Latin, or Aramaic.
- (programming) The lexicology of a programming language. (Usually called lexical structure.)
- (rare) Any dictionary.
- The vocabulary used by or known to an individual. (Also called lexical knowledge)
- A vocabulary specific to a certain subject.
- a baseball lexicon
Related terms 
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- lexicon in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
- lexicon in The Century Dictionary, The Century Co., New York, 1911