Word Origin & History
fetlockearly 14c., fetlak, from a Gmc. source (cf. M.H.G. fizlach, Ger. Fiszloch), perhaps related to the root of Ger. fessel "pastern." The M.E. dim. suffix -ok (from O.E. -oc) was misread and the word taken in folk etymology as being a compound of feet and lock (of hair).