The term "debug" comes from Grace Hopper who coined it while working
on MARK I while in the Navy in the '40's.
The enormous machine failed one evening while she was in command. Since it was
the size to fill a gymnasium and contained thousands of vacuum tubes MARK I
gave off a great deal of heat, so they had opened windows to cool it off. They
discovered that a moth had flown in and was fried- causing MARK I to malfunction.
That evening Grace Hopper taped the moth in the log and noted, "MARK I
was "debugged" tonight." Henceforth, to debug, is to resolve
a problem or malfunction with a computer or computer program. By the way, part
of MARK I and the log - moth and all are in the Smithsonian in DC!