The former term, which derives from a French word meaning "to restore," is a somewhat more genteel word than eating house, eatery, beanery, and hash house (all slang) and café, luncheonette, coffee shop, tavern, grill, and lunch counter. It should be pronounced "RES-tuh-ruhnt" or "RES-tuh-rahnt." A restaurateur (pronounced "RES-tuh-uh'tur") is the manager or owner of a restaurant.
Dictionary of problem words and expressions. Harry Shaw. 1975.