Foul  —adj. 1 offensive; loathsome, stinking. 2 soiled, filthy. 3 colloq. Disgusting, awful. 4 a noxious (foul air). B clogged, choked. 5 obscenely abusive (foul language). 6 unfair; against the rules (by fair means or foul). 7 (of the weather) rough, stormy. 8 (of a rope etc.) Entangled. —n. 1 sport foul stroke or play. 2 collision, entanglement. —adv. Unfairly. —v. 1 make or become foul. 2 (of an animal) foul with excrement. 3 sport commit a foul against (a player). 4 (often foll. By up) a (cause to) become entangled or blocked. B bungle. 5 collide with.  foully adv. Foulness n. [old english]