The two main subjects, which paved the way to the Bluetooth technology, are History and Biology. Neuroscientists studied the way the bio-potentials propagate from one neuron to another and found that the insulating layer at the junction of two neurons, called the Myelin, helps in the propagation of these potentials through electrolytic actions. (I don't have deeper knowledge in Biology) Assuming this transmission of the bio-potentials as the basis, scientists came forward with the idea of Bluetooth data transmission technology. Thus, neurology, which is a branch of biology, provides the technology, it's principle.
The book of history says there lived a King, Harald Blatand, who ruled Denmark and made strenuous efforts to unite Denmark, Sweden and Norway. The idea of BT technology is to interface devices such as mobile phones, computers, printers, keyboards etc. through an open source wireless medium (radiowaves). Since the ultimate aim of the King and the BT technology is one and the same i.e. to unite/interface different parts, the king's name is used as an analogous to the technology. Blatand, in English, means Bluetooth.
When you look at the Bluetooth logo, you'll find that it consists of the symbol 'Asterisk' (It's not asteriks or asterix) and the letter 'B' merged together. In the Runics alphabet system, the equivalent letter for the English alphabet 'H' appears something like an Asterisk. Thus, first letters of the king's first name and second name were taken and merged together to form the symbol. This is how history comes into picture.
The name 'Bluetooth' was initially used as a codeword for the technology when it was at it's infant stage of development. Then, it was accepted by the scientists to be used as the brand name of the technology.