fluid vs light water

fluid

noun
  • A liquid (as opposed to a solid or gas). 

  • Any substance which can flow with relative ease, tends to assume the shape of its container, and obeys Bernoulli's principle; a liquid, gas or plasma. 

  • Intravenous fluids. 

adj
  • In a state of flux; subject to change. 

  • Of or relating to fluid. 

  • Moving smoothly, or giving the impression of a liquid in motion. 

  • Convertible into cash. 

  • Genderfluid. 

light water

noun
  • Foam formed by water and a fluorocarbon surfactant, used in firefighting because it floats on flammable liquids lighter than water. 

  • Water in its standard form of H₂O, containing two protium hydrogen atoms, as opposed to heavy water. 

How often have the words fluid and light water occurred in a corpus of books? (source: Google Ngram Viewer )