A bulb mainly used in the automotive industry with the identification number "194". They are commonly used as license plate light, parking light, etc.
The main reason behind it's name is that it is actually the perfect size of a typical peanut and because these bulbs are so common, and asked at the parts counter so often, it has been given it's own affinitive name: peanut bulb.
Hey Joe, I need two peanut bulbs for repair order number 1234.
Right peanut bulb out! (During a light check)