hydrogen oxide vs serum

hydrogen oxide

noun
  • The simple systematic name for water, H₂O. 

serum

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

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

  • 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. 

  • 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 hydrogen oxide and serum occurred in a corpus of books? (source: Google Ngram Viewer )