[2] In some analyses, compound words and certain classes of idiomatic expressions, collocations and other phrasemes are also considered to be part of the lexicon.
Dictionaries are lists of the lexicon, in alphabetical order, of a given language; usually, however, bound morphemes are not included.
Closed categories, such as determiners or pronouns, are rarely given new lexemes; their function is primarily syntactic.
Open categories, such as nouns and verbs, have highly active generation mechanisms and their lexemes are more semantic in nature.
[4] The mechanisms, not mutually exclusive, are:[5] Neologisms are new lexeme candidates which, if they gain wide usage over time, become part of a language's lexicon.
Comparative historical linguistics studies the evolution of languages and takes a diachronic view of the lexicon.
Over time historical forces work to shape the lexicon,[11] making it simpler to acquire and often creating an illusion of great regularity in language.
Various models of how lexicons are organized and how words are retrieved have been proposed in psycholinguistics, neurolinguistics and computational linguistics.