nasty

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Disgustingly dirty.
2. adj. Physically repellent.
3. adj. Morally offensive; indecent. See Synonyms at offensive.
4. adj. Malicious; spiteful: "Will he say nasty things at my funeral?” ( Ezra Pound).
5. adj. Very unpleasant or annoying: nasty weather; a nasty trick.
6. adj. Painful or dangerous; grave: a nasty accident.
7. adj. Exasperatingly difficult to solve or handle: a nasty puzzle; a nasty problem.
8. n. One that is nasty: "It is the business of museums to present us with nasties as well as with fine things” ( Country Life).

Century Dictionary and Cyclopedia

1. Filthy; dirty; foul; unclean, either literally or figuratively. Physically filthy or dirty.
2. Of filthy habits.
3. Morally filthy; indecent; ribald; indelicate: applied to speech or behavior.
4. Nauseous; disgusting to taste or smell: as, a nasty medicine.
5. In a weakened sense, disagreeable; bad.
6. Foul; stormy; disagreeable; unpleasant: applied to the weather. Compare dirty and foul in the same sense.
7. Troublesome; annoying; difficult to deal with, or threatening trouble; of a kind to be avoided: as, a nasty customer to deal with; a nasty cut or fall.
8. Ill-natured; mean; dishonorable; hateful: as, a nasty remark; a nasty trick.
9. Synonyms 1 and 3. Nasty, Filthy, Foul, Dirty. These words are on the descending scale of strength. Nasty is the strongest word in the language for that which is offensive to sight, smell, or touch by the quality of its uncleanness or uncleanliness, The English fondness for the colloquial use of the word in connection with bad weather, and figuratively for anything disagreeable, is not matched by anything in America; on the contrary, the word is considered too strong for ordinary or delicate use, and foul is used of bad weather. All the words apply to that which is filled or covered in considerable degree with anything offensive. The moral uses of the word correspond with the physical.

Wiktionary

1. n. informal Something nasty.
2. n. euphemistic, preceded by "the" Sexual intercourse.

GNU Webster's 1913

1. adj. Offensively filthy; very dirty, foul, or defiled; disgusting; nauseous.
2. adj. Hence, loosely: Offensive; disagreeable; unpropitious; wet; drizzling.
3. adj. Characterized by obscenity; indecent; indelicate; gross; filthy.
4. adj. Vicious; offensively ill-tempered; insultingly mean; spiteful.
5. adj. slang Difficult to deal with; troublesome.

WordNet 3.0

1. adj. disgustingly dirty; filled or smeared with offensive matter
2. adj. offensive or even (of persons) malicious
3. adj. characterized by obscenity
4. adj. exasperatingly difficult to handle or circumvent