c.1325, 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).
Main Entry: fet·lock Pronunciation: 'fet-"läk Function: noun 1 a: a projection bearing a tuft of hair on the back of the leg above thehoof of a horse or similar animal b: the tuft of hair itself 2: the joint of the limb at the fetlock
[fet-lok] 
