pol·y·glot /ˈpälēˌɡlät / noun = a person who knows and is able to use several languages. Example: "My neighbor Sharon is a translator and is fluent in half a dozen languages besides English."
Dictionary.com gives this definition:
This expression was coined by Shakespeare, who used it literally in Julius Caesar (1:2), where Casca says of a speech by Seneca, deliberately given in Greek so that some would not understand it, "For mine own part, it was Greek to me." It soon was transferred to anything unintelligible.