Etymology
Advertisement
fetlock (n.)
"tuft of hair behind the pastern-joint of a horse," early 14c., fetlak, from a Germanic source (cognates: Dutch vetlock, Middle High German fizlach, German Fiszloch), perhaps from Proto-Germanic *fetel- (source of German fessel "pastern"), from PIE *ped-el-, from root *ped- "foot." The Middle English diminutive suffix -ok (from Old English -oc) was misread and the word taken in folk etymology as a compound of feet and lock (of hair).
Related entries & more 
Advertisement
*ped- 

Proto-Indo-European root meaning "foot."

It forms all or part of: antipodes; apodal; Arthropoda; babouche; biped; brachiopod; cap-a-pie; centipede; cephalopod; cheliped; chiropodist; expedite; expedition; foot; foosball; fetch (v.); fetter; fetlock; gastropod; hexapod; impair; impede; impediment; impeach; impeccable; isopod; millipede; octopus; Oedipus; ornithopod; pajamas; pawn (n.2) "lowly chess piece;" peccadillo; peccant; peccavi; pedal; pedestrian; pedicel; pedicle; pedicure; pedigree; pedology; pedometer; peduncle; pejoration; pejorative; peon; pessimism; petiole; pew; Piedmont; piepowder; pilot; pinniped; pioneer; platypus; podiatry; podium; polyp; pseudopod; quadruped; sesquipedalian; stapes; talipes; tetrapod; Theropoda; trapezium; trapezoid; tripod; trivet; vamp (n.1) "upper part of a shoe or boot;" velocipede.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pad-, accusative padam "foot;" Avestan pad-; Greek pos, Attic pous, genitive podos; Latin pes, genitive pedis "foot;" Lithuanian padas "sole," pėda "footstep;" Old English fot, German Fuß, Gothic fotus "foot."

Related entries & more 
pastern (n.)

late 13c., pastron, "shackle fixed on the foot of a horse or other beast," from Old French pasturon (Modern French paturon), diminutive of pasture "shackle for a horse in pasture," from Vulgar Latin *pastoria, noun use of fem. of Latin pastorius "of herdsmen," from pastor "shepherd" (see pastor). Metathesis of -r- and the following vowel occurred 1500s. The original sense is obsolete; the meaning was extended by 1520s to the part of the horse's leg between the fetlock and the hoof, to which the tether was attached.

Related entries & more