Frequency Dictionary

a type of dictionary, usually monolingual, in which lexical units are characterized according to their frequency of use in a corpus of texts that are representative of the language as a whole, of a particular style, or of an individual author. Such dictionaries are classified according to the type of lexical unit examined as word-form, word (lexeme), stem (used in information science), semantic (words with particular meanings), and word-group frequency dictionaries.

Absolute and relative characteristics of the use of a lexical unit x are distinguished. An absolute characteristic is the frequency f of a given lexical unit x equal to the number of uses of x in the investigated corpus of texts f(x). A frequency dictionary has either f(x) or the normalized frequency f(x)/N, where N is the number of examined words in the text. The relative characteristic of the use of a lexical unit is either the unit’s rank, which is the number of lexical units in the dictionary with an absolute characteristic of use greater than or equal to that of the given lexical unit, or some property that permits the rank to be calculated more or less accurately. Most frequency dictionaries give both absolute and relative characteristics.

Frequency dictionaries are used in the development of efficient methods of teaching language. They are used in information science to isolate key words and in communication theory to create efficient codes.