Such people are strictly amateur compared to, say, Harold Williams, a New Zealander who attended the League of Nations and is said to have spoken comfortably to each delegate in the delegate’s native tongue, or the American Kenneth Hale, who learned passable Finnish (one of about fifty languages he was reputed to speak convincingly) on a flight to Helsinki and allegedly learned Japanese after a single viewing of the Shogun miniseries.
The most famous hyperpolyglot is Giuseppe Mezzofanti, the nineteenth-century Bolognese cardinal who was reputed to speak between thirty and seventy languages, ranging from Chaldaean to Algonquin. He spoke them so well, and with such a feather-light foreign accent, according to his Irish biographer, that English visitors mistook him for their countryman Cardinal Charles Acton. (They also said he spoke as if reading from The Spectator.) His ability to learn a language in a matter of days or hours was so devilishly impressive that one suspects Mezzofanti pursued the cardinalate in part to shelter himself from accusations that he had bought the talent from Satan himself.