dirty

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Covered or marked with dirt or an unwanted substance; unclean.
• adjective Spreading dirt; polluting.
• adjective Apt to soil with dirt or grime.
• adjective Contaminated with bacteria or other infectious microorganisms.
• adjective Squalid or filthy; run-down.
• adjective Obscene or indecent.
• adjective Lewd or lecherous.
• adjective Unethical or corrupt; sordid.
• adjective Malicious or scandalous.
• adjective Not sportsmanlike.
• adjective Acquired by illicit or improper means.
• adjective Slang Possessing or using illegal drugs.
• adjective Unpleasant or distasteful; thankless.
• adjective Extremely unfortunate or regrettable.
• adjective Expressing disapproval or hostility.
• adjective Not bright and clear in color; somewhat dull or drab. Often used in combination.
• adjective Relating to or being a bomb that uses a conventional explosive and radioactive material to contaminate an area with low-level radiation.
• adjective Relating to or being a nuclear weapon that produces a very great amount of long-lived radioactive fallout.
• adjective Stormy; rough.
• intransitive verb To make soiled.
• intransitive verb To stain or tarnish with dishonor.
• intransitive verb To become soiled.

from The Century Dictionary.

• To defile; make filthy; soil; befoul: as, to dirty the clothes or hands.
• To soil or tarnish morally; sully.
• Consisting of or imparting dirt or filth; causing foulness; soiling: as, a dirt mixture; dirt work.
• Characterized by dirt; unclean; not cleanly; sullied: as, dirty hands; dirty employment.
• Appearing as if soiled; dark-colored; impure; dingy.
• Morally unclean or impure; base; low; despicable; groveling: as, a dirty fellow; a dirty job or trick.
• Repulsive to sensitive feeling; disagreeable; disgusting.
• Foul; muddy; squally; rainy; sloppy; uncomfortable: said of the weather or of roads.
• Unclean, soiled, sullied, begrimed.
• 4 and Vile, scurvy, shabby, sneaking, despicable, contemptible, gross, obscene.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Defiled with dirt; foul; nasty; filthy; not clean or pure; serving to defile
• adjective Sullied; clouded; -- applied to color.
• adjective Sordid; base; groveling.
• adjective Sleety; gusty; stormy.
• transitive verb To foul; to make filthy; to soil.
• transitive verb To tarnish; to sully; to scandalize; -- said of reputation, character, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Unclean; covered with or containing unpleasant substances such as dirt or grime.
• adjective That makes one unclean; corrupting, infecting.
• adjective Morally unclean; obscene or indecent, especially sexually.
• adjective Dishonourable; violating accepted standards or rules.
• adjective Corrupt, illegal, or improper.
• adjective Out of tune.
• adjective Of color, discolored by impurities.