Lexicology (from lexiko-, in the Late Greek lexikon) is that part of linguistics which studies words, their nature and meaning, words' elements, relations between words (semantical relations), words groups and the whole lexicon.
The term first appeared in the 1820s, though there were lexicologists in the straight meaning even before that. Computational lexicology as a related field (in the same way that computational linguistics is related to linguistics) deals with the computational study of dictionaries and their contents. An allied science to lexicology is lexicography, which also studies words in relation with dictionaries - it is actually concerned with the inclusion of words in dictionaries and from that perspective with the whole lexicon. Therefore lexicography is the theory and practice of composing dictionaries. Sometimes lexicography is considered to be a part or a branch of lexicology, but the two disciplines should not be mistaken: lexicographers are the people who write dictionaries, they are at the same time lexicologists too, but not all lexicologists are lexicographers. It is said that lexicography is the practical lexicology, it is practically oriented though it has its own theory, while the pure lexicology is mainly theoretical.
Prestructuralist semantics
Semantics as a linguistic discipline has its beginning in the middle of the 19th century, and because linguistics at the time was predominantly diachronic, thus lexical semantics was diachronic too - it dominated the scene between the years of 1870 and 1930. Diachronic lexical semantics was interested without a doubt in the change of meaning with predominantly semasiological approach, taking the notion of meaning in a psychological aspect: lexical meanings were considered to be psychological entities), thoughts and ideas, and meaning changes are explained as resulting from psychological processes.
Structuralist and neostructuralist semantics
With the rise of new ideas after the ground brake of Saussure's work, prestructuralist diachronic semantics was considerably criticized for the atomic study of words, the diachronic approach and the mingle of nonlinguistics spheres of investigation. The study became synchronic, concerned with semantic structures and narrowly linguistic.
Semantic structural relations of lexical entities can be seen in three ways:
As structuralist lexical semantics was revived by neostructuralist not much work was done by them, it is actually admitted by the followers.
It may be seen that WordNet "is a type of an online electronic lexical database organized on relational principles, which now comprises nearly 100,000 concepts" as Dirk Geeraerts states it.
Chomskyan school: interpretative and generative semantics
Followers of Chomskyan generative approach to grammar soon investigated two different types of semantics, which, unfortunately, clashed in an effusive debate, these were interpretative and generative semantics.
Cognitive semantics
Cognitive lexical semantics is thought to be most productive of the current approaches.
Another branch of lexicology, together with lexicography is phraseology. It studies compound meanings of two or more words, as in "raining cats and dogs". Because the whole meaning of that phrase is much different from the meaning of words included alone, phraseology examines how and why such meanings come in everyday use, and what possibly are the laws governing these word combinations. Phraseology also investigates idioms.
Because lexicology studies the meaning of words and their semantical relations, it often is interested in the history of the word, or even in history of vocabulary and lexicon. Etymology is closely used to clarify some questionable meanings, spellings, etc., and is also a matter of lexicography - etymological dictionaries give words with their historical change and development.
As there are many different types of dictionaries, there are many different types of lexicographers.
Questions that lexicographers are concerned with are for example the difficulties in defining what simple words such as 'the' mean, and how compound or complex words, or words with many meanings can be clearly explained. Also which words to keep in and which not to include in a dictionary.
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