mid-13c., "to supply or stock," from Old French estorer "erect, construct, build; restore, repair; furnish, equip, provision," from Latin instaurare "to set up, establish; renew, restore," in Medieval Latin also "to provide, store," from in- "in" (from PIE root *en "in") + -staurare, from PIE *stau-ro-, suffixed extended form of root *sta- "to stand, make or be firm" (compare restore). The meaning "to keep in store for future use" (1550s) probably is a back-formation from store (n.). Related: Stored; storing.