Tetum /ˈtɛtʊm/, also Tetun, is an Austronesian language spoken on the island of Timor. It is spoken in Belu Regency in Indonesian West Timor, and across the border in East Timor, where it is one of the two official languages. In East Timor a creolized form, Tetun Dili, is widely spoken fluently as a second language; without previous contact, Tetum and Tetun Dili are not mutually intelligible.