fob

frequency operated button a.k.a. key fob, FOB

What does fob stand for? The general consensus is that it is not an acronym but rather the name given to the device on a card or key chain that allows people to enter a car or building. However others contend it stands for "frequency operated button."

The word fob is also the name for the form of ID within the device. Many fobs are small flashlights, compasses, calculators, penknives, store discount cards, bottle openers, or USB flash drives.