A double-ended vessel, generally of stainless steel or other metal, one end of which typically measures 1 1/2 fluid ounces, the other typically 1 fluid ounce.

A measure of 1 1/2 fluid ounces of liquor.

A drink of whisky.

To alter or adjust, particularly in ways not originally intended.

“You'll have to jigger it from the original specifications to get it to work.”

To use a jigger.

To move, send, or drive with a jerk; to jerk; also, to drive or send over with a jerk, as a golf ball.