A
lexicon is a
dictionary -- a list of words together with additional information.
In
Linguistics, a lexicon has a slightly more specialized definition, as it includes the
Lexemes used to actualize words. Lexemes are formed according to
morpho-syntactic rules and express
sememes[?].
A lexicon may also be the mental vocabulary in a speaker's mind. Furthermore an indivividual 'lexical knowledge' is a term used in academia to refer to an individual's vocabulary knowledge.