What is the term for the weight of a liquid compared to water?

The term for the weight of a liquid compared to water is specific gravity. Specific gravity is a dimensionless quantity that indicates how many times denser a liquid is compared to water, which has a specific gravity of 1 at 4 degrees Celsius. When a substance's specific gravity is greater than 1, it indicates that the substance is denser than water; if it's less than 1, the substance is less dense than water.

Understanding specific gravity is vital in many applications, including chemical processing, environmental science, and firefighting, where it can help determine how a liquid will behave when mixed with others, as well as its buoyancy properties in water. This knowledge helps firefighters evaluate the hazards associated with various hazardous materials and how to safely manage them during operations.