Dictionary.com
Thesaurus.com

water gauge

American  

noun

  1. any device for indicating the height of water in a reservoir, tank, boiler, or other vessel.

water gauge British  

noun

  1. Also called: water glass.  an instrument that indicates the presence or the quantity of water in a tank, reservoir, or boiler feed

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of water gauge

First recorded in 1700–10

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.