/ ˈleksɪkən; NAmE ; NAmE also -kɑːn/ noun
1.
(also the lexicon ) [ sing. ] ( linguistics ) all the words and phrases used in a particular language or subject; all the words and phrases used and known by a particular person or group of people :
the lexicon of finance and economics
2.
[ C ] a list of words on a particular subject or in a language in alphabetical order :
a lexicon of technical scientific terms
3.
[ C ] a dictionary, especially one of an ancient language, such as Greek or Hebrew
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WORD ORIGIN
early 17th cent.: modern Latin , from Greek lexikon (biblion) (book) of words, from lexis word, from legein speak.