light water vs moisture

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. 

moisture

noun
  • That which moistens or makes damp or wet; exuding fluid; liquid in small quantity. 

  • The state of being moist. 

  • Skin moisture noted as dry, moist, clammy, or diaphoretic as part of the skin signs assessment. 

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