How did Borneo get its name?

The earliest European explorers around Borneo were Portuguese and to a lesser extent Spaniards. They were great seamen. In Portuguese and Spanish a moored ship is "al borneo" when it is free to rotate according to the wind and currents. Perhaps "Borneo" began as a place reference on an early chart, like "Anchorage" became the name of a city in Alaska. Or it could have meant that in this area the fickle winds and currents caused boats to rotate a lot.