(biology) the transmission of hydrogen from water to carbohydrates etc and back to water by living organisms

(inorganic chemistry) A toxic gas, H₂S, smelling like rotten eggs and used in analytical chemistry and industry.

(obsolete, chemistry) hydrogen

To skim the surface of a body of water while moving at high speed.

(nautical) A specific type of motorboat used exclusively for racing. / (aircraft, nautical) A seaplane; any aircraft capable of taking off from, and alighting on the surface of water.

(physics, astronomy) the nucleosynthesis process, in stars of less than 1.2 solar mass, in which hydrogen is converted to helium, deuterium and some lithium

(inorganic chemistry) The ionic base, NH₄⁺OH⁻, obtained by dissolving ammonia in water.

(inorganic chemistry) An alkali, LiOH, used in gas-purification systems in spacecraft, submarines etc, and in the preparation of lithium soap.

(inorganic chemistry) A strong, caustic alkali (NaOH) used in the manufacture of soap, detergents, paper, textiles and having many other industrial applications.

(inorganic chemistry) Alternative spelling of aluminium hydroxide