A lexicon is the vocabulary of a language or subject. "No-hitter," "go-ahead run," and "Baltimore chop" are part of the baseball lexicon.

Lexicons are really dictionaries, though a lexicon usually covers an ancient language or the special vocabulary of a particular author or field of study. In linguistics, the lexicon is the total stock of words and word elements that carry meaning. Lexicon is from Greek lexikon (biblion) meaning "word(book)," ultimately going back to legein, "to speak."

Definitions of lexicon
  1. noun
    a reference book containing an alphabetical list of words with information about them
    synonyms: dictionary
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    bilingual dictionary
    a dictionary giving equivalent words in two languages
    collegiate dictionary, desk dictionary
    an abridged dictionary of a size convenient to hold in the hand
    etymological dictionary
    a dictionary giving the historical origins of each word
    a geographical dictionary (as at the back of an atlas)
    learner's dictionary, school dictionary
    a dictionary specially written for those learning a foreign language
    little dictionary, pocket dictionary
    a dictionary that is small enough to carry in your pocket
    spell-checker, spelling checker
    an electronic dictionary in a word processor that can be used to catch misspelled words
    unabridged, unabridged dictionary
    a dictionary that has not been shortened by the omitting terms or definitions; a comprehensive dictionary
    type of:
    a reference book containing words (usually with their meanings)
  2. noun
    a language user's knowledge of words
    synonyms: mental lexicon, vocabulary
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    type of:
    cognition, knowledge, noesis
    the psychological result of perception and learning and reasoning
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