From WordNet (r) 2.0 (August 2003) [wn]:
nasty
adj 1: offensive or even (of persons) malicious; "in a nasty mood";
"a nasty accident"; "a nasty shock"; "a nasty smell";
"a nasty trick to pull"; "Will he say nasty things at
my funeral?"- Ezra Pound [syn: awful] [ant: nice]
2: exasperatingly difficult to handle or circumvent; "a nasty
problem"; "a good man to have on your side in a tight
situation" [syn: tight]
3: thoroughly unpleasant; "filthy (or foul or nasty or vile)
weather we're having" [syn: filthy, foul, vile]
4: characterized by obscenity; "had a filthy mouth"; "foul
language"; "smutty jokes" [syn: filthy, foul,
smutty]
5: disgustingly dirty; filled or smeared with offensive matter;
"as filthy as a pigsty"; "a foul pond"; "a nasty pigsty of
a room" [syn: filthy, foul]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Nasty \Nas"ty\ (n[.a]s"t[y^]), a. [Compar. Nastier
(n[.a]s"t[i^]*[~e]r); superl. Nastiest.] [For older nasky;
cf. dial. Sw. naskug, nasket.]
1. Offensively filthy; very dirty, foul, or defiled;
disgusting; nauseous.
[1913 Webster]
2. Hence, loosely: Offensive; disagreeable; unpropitious;
wet; drizzling; as, a nasty rain, day, sky.
[1913 Webster]
3. Characterized by obscenity; indecent; indelicate; gross;
filthy.
[1913 Webster]
4. Vicious; offensively ill-tempered; insultingly mean;
spiteful; as, a nasty disposition.
[PJC]
5. Difficult to deal with; troublesome; as, he fell of his
bike and got a nasty bruise on his knee. [slang]
[PJC]
Syn: Nasty, Filthy, Foul, Dirty.
Usage: Anything nasty is usually wet or damp as well as
filthy or dirty, and disgusts by its stickiness or
odor; but filthy and foul imply that a thing is filled
or covered with offensive matter, while dirty
describes it as defiled or sullied with dirt of any
kind; as, filthy clothing, foul vapors, etc.
[1913 Webster]