1. Also called a shot or shot glass, a jigger is a small drinking glass-shaped container that usually holds about 1 1/2 ounces, but can also be a 1- or 2-ounce size. It's generally used to measure liquor. 2. The term is also used to describe the quantity of liquid such a measure holds, as in "a jigger of whiskey. "See also pony; shot.