Profanity, also known as cursing, cussing, swearing, bad language, foul language, obscenities, expletives or vulgarism, is a socially offensive use of language. Accordingly, profanity is language use that is sometimes deemed rude, obscene, or culturally offensive; in certain religions, it constitutes sin. It can show a debasement of someone or something, or be considered an expression of strong feeling towards something. Some words may also be used as intensifiers.

In its older, more literal sense, "profanity" refers to a lack of respect for things that are held to be sacred, which implies anything inspiring or deserving of reverence, as well as behaviour showing similar disrespect or causing religious offense.