Introduction chapter. I. Fundamentals of english lexicography

Etymological Dictionary
Etymological dictionaries are the oldest type of a dictionary except encyclopedias and linguistic glosses or word-books. Its development originates in the 18^th century, from the appearance of Nathaniel Bailey’s Universal Etymological Dictionary of the English Language, originally published in 1721. Since that, etymological dictionaries have been probably the most popular kind of a dictionary, it was developed in the 19^th and 20^th centuries up to the present. Therefore, we can make a conclusion that a question of the origin of the words has always worried lexicographers and the etymological aspect is perhaps one of the most significant for linguistics.
The special feature of an etymology dictionary is that it focuses its attention on the origin of the words and it also deals with prehistory of words. The prehistory often requires the origin of the word in other languages, e.g. 'Clinic' - [comes from Greek <'a bed'], 'Scene' - [comes from Greek < 'a tent']. Another key characteristic of an etymological, or historical dictionary is that the semantic development is extremely important.
Phraseological Dictionary
Phraseological dictionary deals with phraseological units of the language, i.e. idiomatic or colloquial phrases and proverbs.
Phraseological dictionary is also one of the most contemporary types of the dictionaries, unlike encyclopedias, general or etymological dictionaries.
In phraseological dictionaries we can find phraseological word-groups or sentences, arranged, as a rule, into different semantic groups.
The main features of this type of a dictionary is that its organization is rather difficult, unlike all other types of dictionaries. Phraseological units can be classified:

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  according to the ways they are formed,
  
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  according to the degree of the motivation of their meaning,
  
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  according to their structure and according to their part-of-speech meaning.
  

It should also be mentioned that phraseological dictionary can be related to the specialized type of a dictionary since they cover only one restricted area of the word stock, and all the words in this area have very specialized meaning.