WordWeb Online

1. A state characterized by foul or disgusting dirt and refuse
   - filth, filthiness, foulness
    
2. Malevolence by virtue of being malicious, spiteful or nasty
   - cattiness, bitchiness [informal], spite, spitefulness
    
3. The quality of being highly unpleasant
   "I flinched at the nastiness of his wound"

See also: awful, nasty

Type of: malevolence, malevolency, malice, unpleasantness, unsanitariness

Antonym: niceness