Soiled, as with dirt; unclean. Spreading dirt; polluting: The air near the foundry was always dirty. Apt to soil with dirt or grime: a dirty job at the garage. Contaminated with bacteria or other infectious microorganisms. Squalid or filthy; run-down: dirty slums. Obscene or indecent: dirty movies; a dirty joke. Malicious or scandalous: a dirty lie. Unethical or corrupt; sordid: dirty politics. Not sportsmanlike: dirty players; a dirty fighter. Acquired by illicit or improper means: dirty money. Slang Possessing or using illegal drugs. Unpleasant or distasteful; thankless: Laying off workers is the dirty part of this job. Extremely unfortunate or regrettable: a dirty shame. Expressing disapproval or hostility: gave us a dirty look. Not bright and clear in color; somewhat dull or drab. Often used in combination: dirty-blonde hair; dirty-green walls. Producing a very great amount of long-lived radioactive fallout. Used of nuclear weapons. Stormy; rough: dirty weather. To make soiled. To stain or tarnish with dishonor. To become soiled.