Nasty

[nas-tee] /ˈnæs ti/

adjective, nastier, nastiest.
1.
physically filthy; disgustingly unclean:
a nasty pigsty of a room.
2.
offensive to taste or smell; nauseating.
3.
offensive; objectionable:
a nasty habit.
4.
vicious, spiteful, or ugly:
a nasty dog; a nasty rumor.
5.
bad or hard to deal with, encounter, undergo, etc.; dangerous; serious:
a nasty cut; a nasty accident.
6.
very unpleasant or disagreeable:
nasty weather.
7.
morally filthy; obscene; indecent:
a nasty word.
8.
Slang. formidable:
The young pitcher has a good fast ball and a nasty curve.
noun, plural nasties.
9.
Informal. a nasty person or thing.
1.
a combining form with the meaning “nastic pressure,” of the kind or in the direction specified by the initial element:
hyponasty.
/ˈnɑːstɪ/
adjective -tier, -tiest
1.
unpleasant, offensive, or repugnant
2.
(of an experience, condition, etc) unpleasant, dangerous, or painful: a nasty wound
3.
spiteful, abusive, or ill-natured
4.
obscene or indecent
5.
(Brit, informal) nasty piece of work, a cruel or mean person
noun (pl) -ties
6.
an offensive or unpleasant person or thing: a video nasty
combining form
1.
indicating a nastic movement to a certain stimulus: nyctinasty
adj.

c.1400, “foul, filthy, dirty, unclean,” of unknown origin; perhaps [Barnhart] from Old French nastre “miserly, envious, malicious, spiteful,” shortened form of villenastre “infamous, bad,” from vilein “villain” + -astre, pejorative suffix, from Latin -aster.

Alternative etymology [OED] is from Dutch nestig “dirty,” literally “like a bird’s nest.” Likely reinforced in either case by a Scandinavian source (cf. Swedish dialectal naskug “dirty, nasty”), which also might be the source of the Middle English word. Of weather, from 1630s; of things generally, “unpleasant, offensive,” from 1705. Of people, “ill-tempered,” from 1825. Noun meaning “something nasty” is from 1935. Related: Nastily; nastiness.

adjective

Good; stylish; admirable (1834+)

noun