What is lexicology ?

Lexico    : from Greek “speech” or “word”
Logos    : “learning” or “science”

So, lexicology is the study of the history and structure of the vocabulary of a language. Lexicology is the part of linguistics which studies words.

 The aim of lexicology is to define the essence of words.

•  Lexicology studies word formation, semasiology, etymological characteristics of words,phraseological units, lexicography and so on. 
• Lexicology deals with the vocabulary and characteristic features of words and word-groups.
• The term “vocabulary” is used to denote the system of words and word-groups that the language possesses.
• The term “word” denotes the main lexical unit of a language resulting from the association of a group of sounds with a meaning.
• The term ‘word-group” denotes a group of words  which exists in the language as a ready-made unit,has the unity of meaning, the unity of syntactical function.

 According to the theorotical basis of the vocabularies of different languages there are three types of them:

•  Historical lexicology

    deals with the historic change of words in the course of language development.

• Descriptive lexicology

    deals with the vocabulary of a given language at a period of time.

• Contrastive lexicology

    studies languages from the point of view of their identity and differentation

Lexicology is closely connected with other branch of linguistics:

•  The connection between lexicology and phonetics

    Phoneticsis the study and systematic classificatio of the sounds made in spoken utterance, that is, the study of speech sounds. It is closely related  to lexicology. Whitout sound there is no word because every word is a unity of sounds and meaning.

• The connection between lexicology and grammar

    The importance of connection between lexicology with vocabulary/grammar it’s in thr form of words and a combination of words in sentences

• The connection between lexicology and stylistics

    Stylistics is concerned with language variety differing according to user rather than user. Example:
My beloved parent has breathed his last (composed of modifier+subject+verb+object) the stylistics range is a achieved by means of different word choices.

• The connection between lexicology and historical linguistics

    Historical linguistics studies words from the view-point of diachrony, whereas lexicology studiest words from the view-point of both synchrony and diachrony, but especially of synchrony.

https://en.wikipedia.org/wiki/Lexicology
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