Restaurant \RES-ter-uhnt\ or \RES-tuh-rahnt\ or \RES-trahnt\ , noun;
1. An establishment where meals are served to customers
This word is first attested in 1827 and comes from French restaurant. Restaurant, of course, means "restaurant," but its original meaning was "food that restores" from restaurer ("to restore or refresh") from Old French restorer. Restorer derives from Latin restaurare ("repair, rebuild, renew"), which is a combination of re- + -staurare ("back, again" + "restore").
To say that restaurant originally meant "food that restores" kinds of glosses over the whole thing. In the 1400's, Middle French restaurant (or restorant) was any food, cordial, or medicine that restored one's strength or health. By the late 17th century it referred specifically to a "fortifying meat broth" (kind of like our chicken soup), and a century later it had come to refer to the place where that fortifying meat broth was served, and then just "place where food is served."
Those French could have never guessed we'd turn it into this: