étui

case (for glasses, cigars, soap, a viola); holster (for a gun); cover (for an umbrella); cartridge (of a bullet)

Inherited from Middle French étui, from Old French estui (“case, sheath”), of uncertain origin. Possibly a derivative of Old French estuier (“keep, hold”), itself possibly from Vulgar Latin *studiāre, from Latin studium; or, more likely, of Germanic origin, related to Middle High German stūche (“cupping glass”). Compare Occitan estug, Catalan estoig, Spanish estuche, Portuguese estojo, Italian astuccio.