In linguistics, word formation is the creation of a new word. Word formation is sometimes contrasted with semantic change, which is a change in a single word's meaning. The line between word formation and semantic change is sometimes a bit blurry; what one person views as a new use of an old word, another person might view as a new word derived from an old one and identical to it in form; see Conversion (linguistics). Word formation can also be contrasted with the formation of idiomatic expressions, though sometimes words can form from multi-word phrases; see Compound (linguistics) and Incorporation (linguistics).
A similar concept is Derivation.
The following articles describe various mechanisms of word formation: