Définitions
1.NounAny water molecules (H2O) containing two protium (¹H, hydrogen-1) atoms.
2.NounWater in its usual form (as occurs in nature without human intervention), which is mostly of such form.
3.NounWater which has had even the usual small amount of deuterium removed (by human intervention): deuterium-depleted water.
4.NounFoam 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.)