adj., n., adv., & v.
adj. 1 offensive to the senses; loathsome, stinking. 2 dirty, soiled, filthy. 3 colloq. revolting, disgusting. 4 a containing or charged with noxious matter (foul air). b clogged, choked. 5 morally polluted; disgustingly abusive or offensive (foul language; foul deeds). 6 unfair; against the rules of a game etc. (by fair means or foul). 7 (of the weather) wet, rough, stormy. 8 (of a rope etc.) entangled. 9 (of a ship's bottom) overgrown with weeds, barnacles, etc.
n. 1 Sport an unfair or invalid stroke or piece of play. 2 a collision or entanglement, esp. in riding, rowing, or running. 3 a foul thing.
adv. unfairly; contrary to the rules.
v. 1 tr. & intr. make or become foul or dirty. 2 tr. (of an animal) make dirty with excrement. 3 a tr. Sport commit a foul against (a player). b intr. commit a foul. 4 a tr. (often foll. by up) cause (an anchor, cable, etc.) to become entangled or muddled. b intr. become entangled. 5 tr. jam or block (a crossing, railway line, or traffic). 6 tr. (usu. foll. by up) colloq. spoil or bungle. 7 tr. run foul of; collide with. 8 tr. pollute with guilt; dishonour. foul brood a fatal disease of larval bees caused by bacteria. foul mouth a person who uses foul language. foul play 1 unfair play in games. 2 treacherous or violent activity, esp. murder. foul-up a muddled or bungled situation. foully adv. foulness n.
[ OE ful f. Gmc ]