Emily Dickinson Lexicon

FREAK, n. [Ice. freka. Qu. G. frech, bold, saucy, petulant; Dan. frek, id.; Scot. frack, active. The English word does not accord perfectly with the Ger. Dan. and Scot. But it is probably from the root of break, denoting a sudden start.]

1. Literally, a sudden starting or change of place. Hence,
2. A sudden causeless change or turn of the mind; a whim or fancy; a capricious prank. She is restless and peevish, and sometimes in a freak will instantly change her habitation. Spectator.