What's the "een" in Halloween?
mid-13c., "to supply or stock," from Old French estorer "erect, furnish, store," from Latin instaurare "restore," from in- "in" + -staurare, from a noun cognate with Greek stauros "pole, stake" (see steer (v.)). The meaning "to keep in store for future use" (1550s) probably is a back-formation from store (n.).
c.1300, "that with which a household, camp, etc. is stored," from store (v.). Sense of "sufficient supply (of anything)" is attested from late 15c. The meaning "place where goods are kept for sale" is first recorded 1721 in American English (British prefers shop). Stores "articles and equipment for an army" is from 1630s. In store "laid up for future use" (also of events, etc.) is recorded from late 14c. Store-bought is attested from 1952, American English; earlier store-boughten (1883).