Freak

Part of speech: noun (n.)

A sudden causeless change or turn of the mind; a whim of fancy; a capricious prank; a vagary or caprice. She is restless and peevish, and sometimes in a freak will instantly change her habitation. Spectator.

Synonyms: Whim; caprice; folly; sport. See Whim.

Part of speech: verb (v.)

To variegate; to checker; to streak. [R.] Freaked with many a mingled hue. Thomson.