As a Noun: 1. Dust or mud on something which is usually kept clean. English = dirt. 2. Stains, bodily fluids (such as blood) and other things on something which is usually kept clean. English = grime, filth. 3. References to sex in jokes, books, magazines and films that many people find offensive. English = smut, obscenity. As a Verb or Adjective: 1. To have dust, mud, or stains on something and to need to be cleaned. English = (be) dirty, (be) grubby, (be) filthy. 2. To make something dirty by getting dust, mud, or stains on it. English = dirty, soil. Idiomatic English = foul up. 3. Of jokes, books, magazines and films, to refer to sex in a way that many people find offensive. English = (be) dirty, (be) obscene, (be) filthy, (be) smutty.