(n.) A bartending tool used to measure small quantities of liquid. In 19th-century recipes, this measurement was imprecise, but some speculate it correlated with either the pony glass or something around two ounces. Today, the most common versions are made in a conical hourglass shape from stainless steel and come in a range of measurements from one-half to two ounces. When a recipe specifies one jigger, it most likely is calling for one and a half ounces.