1covered or marked with an unclean substance:a tray of dirty cups and saucers her boots were dirty causing a person or place to become unclean:farming is a hard, dirty job (of a nuclear weapon) producing considerable radioactive fallout. 2(of an activity) dishonest; dishonourable:he had a reputation for dirty dealing US informal using illegal drugs. [attributive] informal used to emphasize one’s disgust for someone or something:you dirty rat! 3concerned with sex in a lewd or obscene way:he told a stream of dirty jokes 4(of weather) rough, stormy, and unpleasant.
5(of a colour) not bright or pure; dull:the sea was a waste of dirty grey (of popular music) having a distorted or rasping tone:Nirvana’s dirty guitar sound
used for emphasis:a dirty great slab of stone
make dirty:she didn’t like him dirtying her nice clean towels