Also found in: Thesaurus, Medical, Encyclopedia.


n. Symbol H
A colorless, highly flammable element, that occurs as a diatomic molecule, H2, the lightest of all gases and the most abundant element in the universe, used in the production of synthetic ammonia and methanol, in petroleum refining, in the hydrogenation of organic materials, as a reducing atmosphere, in oxyhydrogen torches, in cryogenic research, and in rocket fuels. Atomic number 1; atomic weight 1.00794; melting point -259.1°C; boiling point -252.8°C; density at 0°C 0.08988 gram per liter; valence 1. See Periodic Table.

[French hydrogène : Greek hudro-, hydro- + French -gène, -gen.]

hy·drog′e·nous (-drōj′ə-nəs) adj.


(Chemistry) of or containing hydrogen


(haɪˈdrɒdʒ ə nəs)

of or containing hydrogen.
References in periodicals archive ?
Rare earth, major and trace elements in Jurassic manganese shales of the Northern Calcaeous Alps: hydrothermal versus hydrogenous origin of stratiform manganese deposits.
Among the topics are modeling approaches to heat and mass transfers in porous wicks, mechanisms of intensive heat transfer for different modes of boiling, practical applications of heat pipes and opportunities for innovative applications because of global warming, sorption systems with heat pipe thermal management for storing and transporting hydrogenous gas, and fluid flow and heat transfer with phase change in minichannels and microchannels.
Treatments were conducted using the changes in molar concentrations of phosphorus produced by the exchange of hydrogenous dipotassium phosphate ([K.