Definition of "hydrometer" [hy•drom•e•ter]

• An instrument used to determine specific gravity, especially a sealed, graduated tube, weighted at one end, that sinks in a fluid to a depth used as a measure of the fluid's specific gravity. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The hydrometer is a sealed glass tube, with a graduated scale somewhat resembling a thermometer."
• "A wine grower uses an instrument called a hydrometer to measure the sugar content in a grape and also measures PH and titratable acidity to determine a grape's maturity or ripeness."
• "Oenofile These five wines may have alcohol levels above 14% (the limit of what the federal government terms "table wine," typically measured with a hydrometer like the one illustrated at right), but they're all wines I'd be glad to have on my table."