Definition of hydrogen in English:



  • A colorless, odorless, highly flammable gas, the chemical element of atomic number 1.

    • ‘Try substituting fluorine for hydrogen in some compounds and the consequences can be dramatic.’
    • ‘The elements of which water is composed, hydrogen and oxygen, both have stable isotopes.’
    • ‘Pour in the water and watch it separate into hydrogen and oxygen, forming a gas to power your vehicle across the floor.’
    • ‘Yes we can say that water is made up of two atoms of hydrogen and one of oxygen but how are these atoms combined to make this substance we call water?’
    • ‘A fuel cell combines hydrogen and oxygen into water and in the process creates electricity that is used to power the car.’
    • ‘Food waste is turned into hydrogen, methane and carbon monoxide by the heat of the exhaust.’
    • ‘The fuel cell combines hydrogen with oxygen from the air to generate electricity that powers the vehicle.’
    • ‘In composition it resembles a small star, with helium and hydrogen as the main gases.’
    • ‘Indeed it's thought that after the big bang the only elements around were hydrogen and helium.’
    • ‘He believes his firm will be in full commercial production turning silicon to hydrogen to be used to power cars.’
    • ‘We know that for a fact because we've measured the isotope ratio of deuterium and hydrogen.’
    • ‘The water could be used for drinking and also split into hydrogen and oxygen to make fuel for future trips.’
    • ‘It was a very dry world, almost no water, and not much carbon, hydrogen or oxygen either.’
    • ‘As the explosive mixture of hydrogen and oxygen ignited, the two turbopumps spun up to speed.’
    • ‘Energy is generated by the reaction of hydrogen and oxygen across a catalytic membrane.’
    • ‘Chemically, oil is made up of chains of carbon, hydrogen and oxygen called fatty acid.’
    • ‘For example, the formula of hydrochloric acid is HCl - one atom of hydrogen and one of chlorine.’
    • ‘We know that the Moon is low on certain chemicals such as hydrogen and carbon.’
    • ‘Once a star has burnt most of its hydrogen to helium, it starts to cool.’
    • ‘In the water molecule there are three atoms: two of hydrogen and one of oxygen.’


Late 18th century: coined in French from Greek hudro- water + -genēs (see -gen).