gremlin: an imaginary creature to whom mechanical problems are attributed. Most often in planes, as shown in a few Bugs Bunny cartoons. This definition has mostly been superseded by the movies from the 80s, which created a whole different sort of Gremlin in the public mind. But what is funny about this word is that is a new creation. It does not have the antiquity which goblin, ogre, elf or giant have; instead it came into being in the years after World War I, in the British Air Force. It referred to a guy who got stuck with the crap jobs at first, and then gradually, by World War II, came to mean a spirit or being that messed with electronics. One suspects that the inter-war gremlins, poor fellows, didn't do the best of jobs, and thus a lot of things got blamed on them. Even in absentia, I would suppose, and thus eventually all problems would be blamed on mysterious gremlins, a word which obviously was taken up by Americans and brought back after the war, and circulated into at least a limited usage, before Steven Spielberg and Joe Dante got a hold of it.
I prefer the original WWII meaning, because most technology seems less than fond of me, and it's nice to have someone to blame, even if it's a latterly-invented imaginary being.