Classification of dictionaries Linguistic dictionaries may be divided into different categories by different criteria

Explanatory dictionaries present a wide range of data, especially with regard to the semantic aspect of the vocabulary items entered.
Specialized dictionaries deal with lexical units only in relation to some of their characteristics, i.e. only in relation to their etymology, frequency, pronunciation, usage. The world famous English Pronouncing Dictionary by Daniel Jones, is considered to provide the most expert guidance on English and American English pronunciation. New 17^th edition contains all the general and encyclopaedic words needed to communicate in modern world – with over 80,000 entries and 220,000 pronunciations.
3. According to the language of explanations, i.e. whether the information about the items entered given in the same language or in another language, all dictionaries are divided into: monolingual and bilingual.
In monolingual dictionaries the words and the information about them are given in the same language.
Bilingual dictionaries are those that explain words by giving their equivalents in another language. They may have two principal purposes: reference for translation and guidance for expression. Bilingual dictionaries must provide an adequate translation of every item in the target language and expression in the source language. The most representative translation dictionaries for English are the New English-Russian Dictionary edited by the supervision of Yu.D. Apresyan and E.M. Mednikova (3 volumes, 250,000 lexical units, 200,000 examples, 700,000 translations), the Modern English-Russian Dictionary by V.K. Müller (160,000 words and expressions).
4. Dictionaries also fall into diachronic and synchronic with regard to time.
Diachronic (historical) dictionaries reflect the development of the English vocabulary by recording the history of form and meaning for every word registered. Diachronic dictionaries, of which The Oxford English Dictionary is the main example, reflect the development of the vocabulary by recording the history of form and meaning for every word registered. They may be contrasted to synchronic or descriptive dictionaries of current English concerned with present-day meaning and usage of words. The boundary between the two is, however, not very rigid: that is to say, few dictionaries are consistently synchronic, chiefly, perhaps, because their methodology is not developed as yet, so that in many cases the two principles are blended. Some synchronic dictionaries are at the same time historical when they represent the state of vocabulary at some past stage of its development.
The Oxford English Dictionary is the accepted authority on the evolution of the English language over the last millennium. It is an unsurpassed guide to the meaning, history, and pronunciation of over half a million words, both present and past. It traces the usage of words through 2.5 million quotations from a wide range of international English language sources, from classic literature and specialist periodicals to film scripts and cookery books. The OED covers words from across the English-speaking world, from North America to South Africa, from Australia and New Zealand to the Caribbean. It also offers the best in etymological analysis and in listing of variant spellings, and it shows pronunciation using the International Phonetic Alphabet. The Second Edition of the OED is currently available as a 20-volume print edition, on CD-ROM, and now also online.