Borneo is Kalimantan

Borneo is the third largest island in the world, after Greenland and New Guinea. It has an area of 743,330 km² (287,000 square miles). Borneo is a large island in Southeast Asia that comprises Malaysia, Indonesia, and the sultanate of Brunei. The Indonesian part of Borneo comprises the southern two-thirds of the island's area and is divided into the four provinces of West, Central, South and East Kalimantan. The Malaysian part comprises the northern coast and is divided into the states of Sarawak and Sabah. The tiny nation of Brunei is wedged between these two Malaysian states.

Borneo was the name of the alternative for Kalimantan. Often this term was used to reconcile the "Borneo" island or "Kalimantan" on the whole. So Borneo is only a western eference; the term is rarely used locally. The name Borneo was only given by the Dutch during their colonial period.

Whereas "Kalimantan" words that most of them was second-hand the royal territory of the Series was only used to refer to the Indonesian part. Whereas the whole part was along with Sabah, Sarawak and Brunei acknowledged as "Borneo".

"Borneo" words etymologically came from Bruneian words, the kingdom that had governed most north territories this island (Sabah, Sarawak), despite now only controlled the area was very just small.