means A pony is a small breed of horse, typically standing under about 14.2 hands at the shoulder, known for being hardy and often used for children to ride.

from "Pony" trots into English in the 1600s, probably from the Scots "powny," which itself likely came from an old French word "poulenet," meaning "little foal" — a diminutive of "poulain," "colt." Chase that back far enough and you reach Latin "pullus," a young animal, a cousin of the same root that gives us "poultry" and "pullet." So a pony is, etymologically, just a baby horse that never grew the name out of itself.