Branches of linguistics. Synchronic vs diachronic approaches to the language study. Lexicology – ‘the science of the word’

Main Problems of Lexicography
The problems of lexicography are connected with the selection of headwords, the number, the structure and contents of the dictionary entry.
Selection of headwords:
-the problem of whether a general descriptive dictionary, whether unilingual or bilingual, should give the historical information about a word;
-selection between scientific and technical terms;
-it is debatable whether a unilingual explanatory dictionary should try to cover all the words of the language, including neologisms, nonce-words, slang etc.;
-the problem of whether the selected units have the right to a separate entry (syntagmatic boundaries of the word) and which are to be included under one common headword (paradigmatic boundaries of the word).
The problem of definitions in a unilingual dictionary:
-a linguistic definition is concerned with words as speech material;
-n encyclopaedic definition is concerned with things for which the words are names.
43.The structure and contents of a dictionary entry depends on the type of the dictionary.
1. diachronic dictionary reflects the development of the vocabulary by recording the history of form and meaning for every word registered. In such dictionaries the entry has the following specific features:
-the arrangement of meanings is chronological;
-the etymology of the word is given an exhaustive treatment;
-the history of the word’s forms and meanings is illustrated by quotations from the works of different periods;
-meanings and quotations are accompanied by dates indicating the time of the word’s first or last registration.
2A synchronic dictionary is concerned with present-day form, meaning and usage of words. Some synchronic dictionaries are at the same time historical when they represent the vocabulary of separate historical periods without tracing the evolution of the language, e.g. Middle English Dictionary.
44. Typology of dictionaries.
A unilingual (explanatory) dictionary is a dictionary in which the entry usually presents the following data: spelling, pronunciation, grammatical characteristics, meanings, illustrative examples, derivatives, phraseology, etymology, synonyms and antonyms, e.g. Collins COBUILD Essential English Dictionary.