astray adv.

c. 1300, a shortening of Old French estraier "wander about, roam, drift, run loose," said of animals, especially a horse without a master, also of persons, perhaps literally "go about the streets," from estree "route, highway," from Late Latin via strata "paved road" (see street). On another theory, the Old French word is from Vulgar Latin *estragare, a contraction of *estravagare, representing Latin extra vagari "to wander outside" (see extravagant). Figurative sense of "to wander from the path of rectitude" is attested from early 14c. Related: Strayed; straying.

c. 1600, of animals; 19c. of persons and things, from stray (n.) and in part a shortening of astray.