1. A mischievous, and often invisible, being, said by airplane pilots from WWII to cause engine troubles and mechanical difficulties.
2. Any cause of difficulty, troubles, etc.
EX. Gremlins (1984) was a film that had a considerable effect on my childhood; one of my first stuffed toys was a really good make of Gizmo that I still have somewhere. His eyes are a little scratched from being bumped on jungle gyms, a few stray strands hang from an ear, but he is still the same guy that was my friend when I was little. There is another side to the coin.
Gremlins was one of the first horror movies I ever saw, on TV, and gave me some rather unpleasant nightmares. A particularly frightening one involved me waking up, going to my parent's room, and finding one of these monster about to attack my Mom and Dad.
As for today, I think that the film and its title characters have a weird place in the back of my mind, and I wouldn't be surprised if I turn to them for inspiration. I definitely recommend the film, especially around Christmas as a darker classic, if nothing but to better understand the creation of the "little monsters" comedic horror film and to appreciate the soundtrack & puppetry.