A stream gauge is a device used to measure the water level of a river or stream. There are several synonyms for the term "stream gauge", including "water gauge", "flow meter", "water level sensor", and "streamflow gauge". A water gauge is a tool used to measure the water level of a body of water. A flow meter is a device that measures the flow rate or volume of a liquid or gas. A water level sensor is any device used to measure the level of water in a given location. Finally, a streamflow gauge is a type of water gauge that measures the rate of flow of a river or stream. These synonyms are often used interchangeably and refer to the same type of instrument.