1284, "shackle fixed on the foot of a horse or other beast," from O.Fr.
pasturon, dim. of
pasture "shackle for a horse in pasture," from V.L.
*pastoria, noun use of fem. of L.
pastorius "of herdsmen," from
pastor "shepherd" (see
pastor). Metathesis of
-r- and following vowel occurred 1500s. Sense extended (1530) to part of the leg to which the tether was attached.