All the existing dictionaries may be subdivided into two groups:
- non-linguistic or encyclopaedic dictionaries (encyclopaedias) and
- linguistic or philological dictionaries. Linguistic dictionaries may be monolingual or one-language (unilingual) dictionaries and bilingual - in two languages (sometimes in several languages, called multilingual or polyglot dictionaries). Unilingual explanatory dictionaries are those in which every word is explained and defined in the same language.
With regard to time unilingual dictionaries are subdivided into diachronic and synchronic or descriptive.
Linguistic dictionaries are also subdivided into general and restricted dictionaries.
General dictionaries represent the vocabulary as a whole with a degree of completeness depending upon the scope and bulk of the dictionary.
Restricted dictionaries cover only a certain specific part of the vocabulary, for example, terminological dictionaries, phraseological dictionaries, dictionaries of slang; dictionaries of synonyms, antonyms, homonyms, etc.
General dictionaries with regard to the type of information about the word may be subdivided into explanatory and specialized.
Explanatory dictionaries provide a wide range of information about the vocabulary items focusing on the definition of the word meaning.
Specialized dictionaries, which are also called general dictionaries with specific aims, provide information on a certain specific aspect of the word singled out: pronouncing dictionaries, orthographic, etymological dictionaries, dictionaries of frequency, etc.
Dictionaries recording the complete vocabulary of some author are called concordances. A thesaurus is an ideographic dictionary, that supplies words by which a given idea may be expressed.
According to their scope dictionaries may be 1) pocket or small- size dictionaries, 2) concise or middlesize dictionaries and 3) large dictionaries.
The new branch of lexicography, computational lexicography, deals with the compilation, design, use and evaluation of electronic dictionaries. There are two main types of electronic dictionaries: CD- ROM dictionaries and on-line dictionaries.
The most debatable problems of lexicology are those connected with the choice of vocabulary items and the ways of presenting the information about them.
