A common size of
battery used in many household
electric devices and
toys. An AA battery is a cylinder, roughly 2 inches in length (5 cm), and 1/3 inch in diameter. One end has the positive terminal, the other the negative. The positive end is distinguished by a small nub.
They are rated at 1.5
volts, and have varying
lifetimes depending on the manufacturer and the insides of the battery. Some newer models come
built-in with a charge tester.
It has been noted
elsewhere that a AA battery is technically not a battery, but a
dry cell. But for all practical purposes, they're called batteries. Can't fight English, I suppose.