water glass

definition: clock that measures time by the escape of water
example:
speech part: noun
synonyms: water clock
definition: gauge for indicating the level of water in e.g. a tank or boiler or reservoir
example:
speech part: noun
synonyms: water gauge water gage
definition: a glass for drinking water
example:
speech part: noun
synonyms:
definition: a viscous glass consisting of sodium silicate in solution
example:
speech part: noun
synonyms: soluble glass sodium silicate

How water glass is being used?