Definitions by CK454

a fifth 

A one fifth of a gallon bottle of alcohol, or 4/5 of a quart. Previous to the US converting to the metric system, hard liquor was sold in 1/5 gallon bottles. Slightly larger than the current 750ml, but still used to refer to a 750ml of booze

Pick me up a fifth of Jim Beam.

a fifth by CK454 December 30, 2008