Английский Этимологический словарь - pony (n.)

- 1659, powny, from Scottish, apparently from Fr. poulenet "little foal," dim. of O.Fr. poulain "foal," from L.L. pullamen "young of an animal," from L. pullus "young of a horse, fowl, etc." German, sensibly, indicates this animal by attaching a dim. suffix to its word for "horse," which might yield Mod.Eng. *horslet. Meaning "crib of a text as a cheating aid" (1827) and "small liquor glass" (1849) both are from notion of "smallness" (the former also "something one rides"). Pony Express began 1847. Ponytail, girls' hairstyle, first recorded 1952.