Where did they get their name ?

In the band's very early beginnings, circa 1978, Adam Clayton asked Steve Averill (formerly known as Steve Rapid of the band Radiators From Space) to help the band come up with a good name. Averill was interviewed by Hot Press magazine in 2001 and gave this answer when asked about how he helped U2 choose the band's name:
"When I first met them they didn't really know what they wanted to do, what type of band they really wanted to be. But they had qualified for the final of that band competition in Limerick and they needed to decide on a name. Adam liked names like XTC, which were short and crisp and could mean a lot or mean very little. So I made a list of ten and I put U2 on the bottom. I thought it was strong graphically and it had a variety of connotations without meaning something specific. It was short and stood out from the band names common at the time. After we discussed the list we decided to go for U2 for all those reasons."
There have also been many stories told about how the band's name is taken from the U-2 spy plane, and those stories gained favor with the connection of the famous Francis Gary Powers U-2 incident which occurred on May 1, 1960, and the fact that Bono was born just nine days later. These stories seem to be a stretch at best, and Averill's answer above makes no mention of the spy plane connection.
Averill, it should be noted, didn't stop helping U2 when he helped choose the name. He was also asked to manage U2 but declined, opting instead to handle U2's visual aspects. Averill and his partners at Four 5 One (formerly Works Associates / ABA) in Dublin also design U2 album covers, t-shirts, backstage passes, tour programmes, and even the symbols on Edge's hats during the Zoo TV Tour.