last changed in 2002
Word-formation is the (study of the) relationships among lexemes that are partially similar to each other. For example, FARM and FARMER must belong to different lexemes because they have different stems and senses and these connections could not be expressed if they were treated as a single lexeme; but they are closely related in both form and meaning. Many other pairs of lexemes are related in the same way, so we need to be able to express generalisations about relations between lexemes by means of `word-formation rules'. Some such rules involve regular morphological variation, in which case they belong to derivational morphology. Others involve no morphological difference at all (e.g. between the WALKn and WALKv, the noun and verb), or an irregular one (e.g. MALE: FEMALE).
The name `word-formation' is used because these patterns often form the basis for creating new lexemes (eg. XEROXER), but there are many other ways of creating new vocabulary, not least of which is borrowing material from another language. One difficulty with the study of word-formation is that it lies uncomfortably between 'rule-governed behaviour' (e.g. XEROXER) and 'creativity' (e.g. borrowing).
This is an article from the Encyclopedia of Word Grammar and English grammar. If you refer to it, please give the url as "http://tinyurl.com/wg-encyc".