foul

How to sign: disgustingly dirty; filled or smeared with offensive matter
"as filthy as a pigsty"; "a foul pond"; "a nasty pigsty of a room";

Similiar / Same: filthy, nasty

foul

How to sign: offensively malodorous
"a putrid smell";

Similiar / Same: fetid, foetid, foul-smelling, funky, smelly, noisome, stinking, putrid

foul

How to sign: highly offensive; arousing aversion or disgust
"a disgusting smell"; "distasteful language"; "a loathsome disease"; "the idea of eating meat is repellent to me"; "revolting food"; "a wicked stench";

Similiar / Same: disgusting, disgustful, loathly, repelling, revolting, skanky, yucky, distasteful, loathsome, repellent, repellant, wicked

foul

How to sign: become or cause to become obstructed
"The leaves clog our drains in the Fall"; "The water pipe is backed up";

Similiar / Same: clog, clog up, congest, choke off, back up, choke

Categories: block, close up, impede, jam, obstruct, obturate, occlude

Within this category: crap up, gum up, silt up, stuff

foul

How to sign: violating accepted standards or rules
"a dirty fighter"; "used foul means to gain power"; "a nasty unsporting serve"; "fined for unsportsmanlike behavior";

Similiar / Same: unsporting, unsportsmanlike, cheating, dirty

foul

How to sign: spot, stain, or pollute
"The townspeople defiled the river by emptying raw sewage into it";

Similiar / Same: befoul, maculate, defile

Categories: attaint, disgrace, dishonor, dishonour, shame

foul

How to sign: thoroughly unpleasant
"filthy (or foul or nasty or vile) weather we're having";

Similiar / Same: vile, filthy, nasty