Conversion (word formation)

In linguistics, conversion, also called zero derivation or null derivation, is a kind of word formation involving the creation of a word (of a new part of speech) from an existing word (of a different part of speech) without any change in form, which is to say, derivation using only zero. For example, the noun green in golf (referring to a putting-green) is derived ultimately from the adjective green.

Conversions from adjectives to nouns and vice versa are both very common and unnotable in English; much more remarked upon is the creation of a verb by converting a noun or other word (for example, the adjective clean becomes the verb to clean).