Final answer:
A fifth is a term for a common quantity of alcohol, which is equivalent to a fifth of a gallon or 750 milliliters. This unit of measurement originates from the old English system of measuring liquids.
Step-by-step explanation:
A "fifth" is a common quantity of alcohol that refers to a fifth of a gallon, which is equal to 750 milliliters or approximately 25.4 fluid ounces.
This measurement is based on the old English system of measuring spirits and other liquids. In the United States, a typical bottle of liquor sold at a store is often in the size of a fifth.
It's essential to understand these measurements as they are standards of comparison for volumes and can be related to dosages for medications, where precision is vital and mistakes can lead to severe consequences.