freak

First appears c. 1567. The sense "sudden change of mind, a whim" is of uncertain origin. Probably from a dialectal word related to Middle English frekynge (“capricious behavior; whims”) and Middle English friken, frikien (“to move briskly or nimbly”), from Old English frician (“to leap, dance”), or Middle English frek (“insolent, daring”), from Old English frec (“desirous, greedy, eager, bold, daring”), from Proto-West Germanic frek, from Proto-Germanic frekaz, *frakaz (“hard, efficient, greedy, bold, audacious”) (in which case, it would be related to the noun under Etymology 2). Compare Old High German freh (“eager”), Old English frēcne (“dangerous”). For the meaning development compare Russian заско́к (zaskók) akin to скок (skok), скака́ть (skakátʹ).

From Middle English freke, freike (“a bold man, warrior, man, creature”), from Old English freca (“a bold man, warrior, hero”), from Proto-Germanic frekô (“an active or eager man, warrior, wolf”), from frekaz (“active, bold, desirous, greedy”), from Proto-Indo-European pereg-, spereg- (“to shrug, be quick, twitch, splash, blast”). Cognate with Old Norse freki (“greedy or avaricious one, a wolf”), Old High German freh (“eager”), German frech, Old English frēcne (“dangerous, daring, courageous, bold”).