NASTY ( 'nas-te ) adj. 1. Twisted. 2. Spitefully unfair. 3. Causing dangerous and severe laughter. SYNONYMS: Hilarious. Deliciously fun. Sample usage: "What a nasty, wicked book, filled with mayhem and mischief" "Only nasty criminals would kidnap a cuddly teddy bear!" "Monsters attacking 'cause a kid picks his nose? That's nasty." "A witch on the Internet, a superhero who farts? All nasty too!" ANTONYMS: Nice. Boring. Plain old ordinary.