light water vs serum

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. 

serum

noun
  • A watery liquid from animal tissue, especially one that moistens the surface of serous membranes or that is exuded by such membranes when they become inflamed, such as in edema or a blister. 

  • Blood serum from the tissues of immunized animals, containing antibodies and used to transfer immunity to another individual. 

  • The watery portion of certain animal fluids like blood, milk, etc; whey. 

  • The clear yellowish liquid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. 

  • An intensive moisturising product to be applied after cleansing but before a general moisturiser. 

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