Fuck is an English word that, as a verb, means "to have sexual intercourse". As a noun it may describe a contemptible person (also fucker) or a sexual partner. It can be used as an interjection, and its participle fucking is sometimes used as a strong emphatic. The verb to fuck may be used transitively or intransitively, and it appears in compounds, including fuck off, fuck up, and fuck with. In less explicit usages (but still regarded as vulgar), fuck can mean to mess around, or to deal with unfairly or harshly. In a phrase such as "don't give a fuck", the word is the equivalent of "damn", in the sense of something having little value. In "what the fuck", it serves as a meaningless intensive.
The word's use is considered obscene in polite circles, but may be common in informal and domestic situations. It is unclear whether the word has always been considered vulgar, and if not, when it first came to be used to describe (often in an extremely angry, hostile or belligerent manner) unpleasant circumstances or people in an intentionally offensive way, such as in the term motherfucker, one of its more common usages in some parts of the English-speaking world.