Pronunciation: (mu-lā'u),[key] —n. 1. See Malay Peninsula. 2. Federation of. Formerly, Malay States, Malay'an Un'ion. a former federation of 11 states in the S Malay Peninsula: a British protectorate 1948–57; now forms part of Malaysia. 50,690 sq. mi. (131,287 sq. km). Cap.: Kuala Lumpur. Cf. Malaysia (def. 1).