zločest

1. (of a person) mean; nasty; wicked
   Bio je zločest prema svima oko sebe. — He was mean to everyone around him.
   To je bila baš zločesta šala. — That was a really nasty joke.
2. Croat. (of a child, animal) naughty; mischievous
   Zločesti mačak je opet srušio čašu sa stola. — The naughty cat knocked a glass off the table again.

The word is more common in Croatia; in Serbia zao, pakostan are usually preferred. In the sense 'naughty, mischievous' (of a child, animal), in Serbia: nestašan, nevaljao.