large island in the Malay Archipelago, southwest of the Philippines: the S portion ( Kalimantan) is a part of Indonesia; the N portion is composed of the Malaysian states of Sabah & Sarawak, and of Brunei: total area, c. 288,000 sq mi (745,917 sq km)
An island of the western Pacific Ocean in the Malay Archipelago between the Sulu and Java Seas southwest of the Philippines. It is the third-largest island in the world. The sultanate of Brunei is on the northwest coast; the rest of the island is divided between Indonesia and Malaysia.
Probably from Sanskrit वरुणद्वीप (varuṇa-dvīpa, “island of Varuna”).