There is some disagreement on the definition of lexicology, as distinct from lexicography. Some use "lexicology" as a synonym for theoretical lexicography; others use it to mean a branch of linguistics pertaining to the inventory of words in a particular language. A person devoted to lexicography is called a lexicographer.
General lexicography focuses on the design, compilation, use and evaluation of general dictionaries, i.e. dictionaries that provide a description of the language in general use. Such a dictionary is usually called a general dictionary or LGP dictionary. Specialized lexicography focuses on the design, compilation, use and evaluation of specialized dictionaries, i.e. dictionaries that are devoted to a set of linguistic and factual elements of one or more specialist subject fields, e.g. legal lexicography. Such a dictionary is usually called a specialized dictionary or Language for specific purposes dictionary and following Nielsen 1994, specialized dictionaries are either multi-field, single-field or sub-field dictionaries. It is now widely accepted that lexicography is a scholarly discipline in its own right and not a sub-branch of applied linguistics, as the chief object of study in lexicography is the dictionary.
Coined in English 1680, the word "lexicography" derives from the Greek λεξικογράφος lexikographos, "lexicographer", from λεξικόν lexicon, neut. of λεξικός lexikos, "of or for words", from λέξις lexis, "speech", "word", and γράφω grapho, "to scratch, to inscribe, to write".
Practical lexicographic work involves several activities, and the compilation of well-crafted dictionaries requires careful consideration of all or some of the following aspects:
profiling the intended users and identifying their needs
choosing lemma forms for each word or part of word to be lemmatized
specifying pronunciations of words
labeling definitions and pronunciations for register and dialect, where appropriate
selecting equivalents in bi- and multi-lingual dictionaries
translating collocations, phrases and examples in bi- and multilingual dictionaries
designing the best way in which users can access the data in printed and electronic dictionaries
One important goal of lexicography is to keep the lexicographic information costs incurred by dictionary users as low as possible. Nielsen suggests relevant aspects for lexicographers to consider when making dictionaries as they all affect the users' impression and actual use of specific dictionaries. Theoretical lexicography concerns the same aspects as lexicography, but aims to develop principles that can improve the quality of future dictionaries, for instance in terms of access to data and lexicographic information costs. Several perspectives or branches of such academic dictionary research have been distinguished: 'dictionary criticism', 'dictionary history', 'dictionary typology', 'dictionary structure', 'dictionary use', and 'dictionary IT'. One important consideration is the status of 'bilingual lexicography', or the compilation and use of the bilingual dictionary in all its aspects. In spite of a relatively long history of this type of dictionary, it is often said to be less developed in a number of respects than its unilingual counterpart, especially in cases where one of the languages involved is not a major language. Not all genres of reference works are available in interlingual versions, e.g. LSP, learners' and encyclopedic types, although sometimes these challenges produce new subtypes, e.g. 'semi-bilingual' or 'bilingualised' dictionaries such as Hornby's Advanced Learner's Dictionary English-Chinese, which have been developed by translating existing monolingual dictionaries.