Definitions

1. noun

An instrument used to measure the specific gravity of liquids, typically by determining the relative weight of a sample compared to the weight of an equal volume of water.

“The chemist used a hydrometer to determine the density of the unknown liquid.”

2. noun

A device for measuring the alcohol content of beverages, such as beer or wine.

“The bartender used a hydrometer to check the proof of the whiskey.”