Lexicology as a branch of linguistics studying the vocabulary. The term lexicology is composed of two Greek morphemes (lexis – word / phrase, logos – studying).
Thus the term lexicology literally means the department of knowledge, studying words and phrases. The word is the basic unit of the language resulting from the association of a particular group of sounds with a particular grammatical employment, capable to function alone and characterized by positional mobility within a sentence, semantic integrity and morphological uninterrupability.
All the words in a language make up what is generally called the vocabulary of the language and the basic task of lexicology is to study and to describe systematically the English vocabulary with respect to its origin, development and use. Distinction is usually made between general and special lexicology
General lexicology is a part of General linguistic. It studies the vocabulary of the language irrespective of the specific features of this language.
Special lexicology is the lexicology of a particular language and it describes the vocabulary of the given language.
There are two principal approaches to the study of language
1). Diachronic ( -al, -istic) or historical or etymological.
The diachronic approach in terms of Special Lexicology deals with the changes and the development of vocabulary in the course of time. It is special Historical Lexicology that deals with the evolution of the vocabulary units of a language as time goes by. An English Historical Lexicology would be concerned, therefore, with the origin of English vocabulary units, their change and development, the linguistic and extralinguistic factors modifying their structure, meaning and usage within the history of the English language.
2). Synchronic (-al, istic) or descriptive.
the synchronic state of a language system is a result of a long process of linguistic evolution, of its historical development.
Needless to say, one can hardly overestimate the importance of Contrastive Lexicology as well as of Comparative Linguistics in general for the purpose of class-room teaching of foreign languages. Of primary importance in this respect is the comparison of the foreign language with the mother tongue.
1). Comparative lexicology – specifies both common and different features of one phenomenon
2).Contrastive lexicology – emphasis only different features of one and the same phenomenon.