Learn how to say Lexicon correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word lexicon:
the vocabulary of a person, language, or branch of knowledge:
the size of the English lexicon
a dictionary, especially of Greek, Hebrew, Syriac, or Arabic:
a Greek-Latin lexicon
early 17th century: modern Latin, from Greek lexikon (biblion) ‘(book) of words’, from lexis ‘word’, from legein ‘speak’