lexicon (lexical, lexically): the set of morphemes in a language, together with non-productively formed complex [2] words as well as idioms and other stock phrases. These are structures a speaker knows as complete units and can use without having to compute their meanings from their parts. A dictionary (also sometimes called a lexicon) is a book which lists items in a language's lexicon, especially words, with a brief indication of their meanings and use. Contrast grammar, syntax, morphology, phonology, semantics. [Spanish: léxico]