Definition of hydrogen in US English:

hydrogen

noun

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

    Hydrogen is the lightest of the chemical elements and has the simplest atomic structure, a single electron orbiting a nucleus consisting of a single proton. It is by far the commonest element in the universe, although not on the earth, where it occurs chiefly combined with oxygen as water

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

Origin

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

Pronunciation

hydrogen

/ˈhīdrəjən//ˈhaɪdrədʒən/