Main Entry: water glass

Function: noun

Date: 1612

1 : a glass vessel (as a drinking glass) for holding water
2 : an instrument consisting of an open box or tube with a glass bottom used for examining objects in or under water
3 : a substance that consists usually of the silicate of sodium, is found in commerce as a glassy mass, a stony powder, or dissolved in water as a viscous syrupy liquid, and is used especially as a cement, a protective coating, and as a fireproofing agent