light water

Noun

light water (uncountable)

1. Water in its usual form (as occurs in nature without human intervention), which is mostly of such form.

   Synonyms:

   diprotium monoxide

2. Water which has had even the usual small amount of deuterium removed (by human intervention): deuterium-depleted water.

   Synonyms:

   diprotium monoxide

3. Foam formed by water and any of various additives, used in firefighting because it floats on flammable liquids lighter than water. (The additives were originally fluorocarbon surfactants but today are increasingly fluorine-free.)
   • The light water (AFFF) of the TACR was to be backed up by fluorinated protein foam instead of standard protein foam.2001, Roger C. Mardon, An Illustrated History of Fire Engines, →ISBN, page 112
   • These fires can be extinguished with water spray, alcohol-resistant foam, light water, vaporising liquids ("Halons"), carbon dioxide and dry powder.2014, John R. Ridley, Safety at Work, →ISBN, page 504