This article is from the U2 FAQ, by Maryann Stump firstname.lastname@example.org with numerous contributions by others.
[M] The reason for the band picking the name U2 is not really known. For
one thing, the U2 is a spy plane that
was in service during the late '50s and '60s. There was a U2 that was
involved in a crash over the old Soviet
Union on 4 May 1960 (four days before Bono was born). The name U2 is
also a pun, as in you too or you two.
The name seemed to be sufficiently vague to work as the name of the band
we now know and love.
[JC] The U2 model was an American spy plane used after WWII. It is famous
for the 'U2 incident'. This plane
was used for high altitude reconnaissance before the use of satellites
and was not supposed to be detectable by
radar. The plane was shot down over Soviet Russia in the late 50's, and
the pilot, Francis Gary Powers,
captured. When the Soviets announced to Dwight Eisenhower they had shot
down a U2 spy plane, his retort was
'What plane?' Yes, a great moment in Presidential history.) The band took
their name after this plane.
[PG] Before U2, the group had two other names (for a short period):
'Feedback' and 'The Hype'.
[GM] 1960 was the year. Eisenhower knew about U-2 flights over the USSR,
but he wasn't just going to come
out and admit it in case the Soviets were bluffing. Adam said he liked
names like XTC, they had Steve Averill
come up with a bunch of suggestions. They didn't exactly love the name
U2, but they couldn't come up with a
better name, so they used it. The above reasons why it was the best are