Longman Dictionary of Contemporary English - foul

~1 adj 1 »SMELL/TASTE« a foul smell or taste is very unpleasant  (I gulped down some water to take the foul taste out of my mouth. | foul-tasting/foul-smelling)  (The bags of garbage had been piled up in a foul-smelling heap.) 2 in a foul mood/temper especially BrE in a very bad mood and likely to get angry  (He's in a foul mood today, isn't he?) 3 »UNPLEASANT« especially BrE very unpleasant  (I've had an absolutely foul day.) 4 »AIR/WATER« very dirty  (The water in the harbour was foul with oil.) 5 foul language rude and offensive words  (I've never heard such foul language in all my life!) 6 »WEATHER« especially BrE if the weather is foul, it is stormy and windy, with a lot of rain or snow 7 »EVIL« especially literary evil or cruel  (foul deeds)  (- see also by fair means or foul fair1 (13), fall foul of fall1 (28)) - foully adv - foulness n ~2 v 1 a) if a player fouls in a game of sport, or fouls another player, they do something that is not allowed by the rules  (An Everton player had been fouled in the penalty area.) b) to hit a ball outside the limit of the playing area in baseball  (On average, most batters foul at least one ball in each at bat.) 2 formal to make something very dirty, especially with waste  (A thick column of black smoke rose from the wreck, fouling the air.) 3 also foul up if a rope, chain, or part of a machine fouls or if something fouls it, it twists or cannot move properly  (Check that nothing can foul the moving parts.) foul up phr v informal 1 T foul something up) to spoil something  (The weather really fouled up our vacation plans.) 2 T foul something up) to do something wrong or spoil something by making mistakes  (Glen completely fouled up the seating arrangements.) ~3 n an action in a sport that is against the rules  (That was a foul - he touched the ball with his hand!)