c. 1300, "land covered with vegetation suitable for grazing;" also "grass eaten by cattle or other animals," from Old French pasture "fodder, grass eaten by cattle" (12c., Modern French pâture), from Late Latin pastura "a feeding, grazing," from Latin pastus, past participle of pascere "to feed, graze," from PIE root *pa- "to feed." To be out to pasture in the figurative sense of "retired" is by 1945, from where horses were sent (ideally) after their active working life.
