One of the most common wireless standards carries the nickname of a Viking-age king. It was never supposed to be the final name.
The king was Harald Gormsson, who ruled Denmark from about 958 to about 986, and Norway for part of that time. Around 965 he raised the larger of the Jelling stones in memory of his parents. Its inscription credits him with winning all of Denmark and Norway and making the Danes Christian.
His nickname, Bluetooth, is first recorded in the Roskilde Chronicle, written around 1140, as blatan. In Old Norse it would be blátǫnn. Nobody knows why he had it. The usual explanation is a conspicuous bad tooth. The Old Norse blár meant a dark blue-black, so a dead, darkened tooth would fit. Another scholar has suggested it meant "dark thane," with the English word thegn garbled on its way back into Norse.
The modern name came from a pub crawl. In his own account for EE Times, Intel engineer Jim Kardach describes a trip to Toronto with Sven Mattisson of Ericsson. The two had pitched rival short-range radio plans and been turned down. Over drinks, Mattisson talked about The Long Ships, a Swedish novel by Frans G. Bengtsson, in which Harald Bluetooth appears.
Back home, Kardach read about the king in a history of the Vikings. He saw the parallel. Harald had united Denmark, and the new standard was meant to unite the PC and mobile phone industries. Wikipedia dates his proposal to 1997, while the Bluetooth SIG says 1996.
Bluetooth was only a placeholder. Kardach lists the programs that came before it: Business-RF at Intel, MC-Link from Ericsson and Low Power RF from Nokia. Marketing floated Flirt. The board voted 4 to 1 for PAN, for Personal Area Networking. Then a search turned up tens of thousands of internet hits for PAN, making it a poor trademark. No search had been done on the backup, RadioWire. With the launch close, the code name became the real one.
The king even made it into the logo. It is a bind rune joining two Younger Futhark runes, Hagall and Bjarkan. They stand for H and B, Harald Bluetooth's initials.
The Bluetooth Special Interest Group launched in May 1998 with Ericsson, Intel, Nokia, Toshiba and IBM. A thousand-year-old nickname of uncertain meaning now sits on phone settings screens around the world.