hydrogen

noun

hy·​dro·​gen ˈhī-drə-jən 

-dər-

: a nonmetallic gaseous chemical element with atomic number 1 that is the simplest and lightest of the elements and that is used especially in the processing of fossil fuels and the synthesis of ammonia

—often used before another noun

hydrogen gas

hydrogen atoms

a hydrogen vehicle

the hydrogen industry

see Chemical Elements Table compare deuterium, tritium

hydrogenous

hī-ˈdrä-jə-nəs 

adjective

Examples of hydrogen in a Sentence

Recent Examples on the Web

The plasma turned into a fog of neutral hydrogen and helium gas, but those density waves were frozen into the distribution of matter, a distribution that persists to this day, albeit on much larger scales than back then. —Keith Cooper, Space.com, 22 Jan. 2025

Green hydrogen production costs are projected to fall to €5 - 7 per kilogram by 2025, while capacity is set to double, with China expected to hold half by 2027. —Sarwant Singh, Forbes, 22 Jan. 2025

Financing for hydrogen exploration and development remains uncertain, and unclear demand forecasts complicate market growth. —Kristen Waggoner, Newsweek, 21 Jan. 2025

The fuel was subjected to full reactor heat and hydrogen gas and kept there for 20 minutes – about what a nuclear engine would have to endure during a boost maneuver. —David Szondy, New Atlas, 20 Jan. 2025

Word History

Etymology

French hydrogène, from hydr- + -gène -gen; from the fact that water is generated by its combustion

First Known Use

1788, in the meaning defined above

Phrases Containing hydrogen

• heavy hydrogen
• hydrogen bomb
• hydrogen bond
• hydrogen bromide
• hydrogen chloride
• hydrogen cyanide
• hydrogen fluoride
• hydrogen iodide
• hydrogen ion
• hydrogen peroxide
• hydrogen sulfide

Kids Definition

hydrogen

noun

hy·​dro·​gen ˈhī-drə-jən 

: a chemical element that is the simplest and lightest of all chemical elements and is normally found alone as a colorless odorless highly flammable gas having two atoms per molecule see element

hydrogenous

hī-ˈdräj-ə-nəs 

adjective

Etymology

from French hydrogène "hydrogen," from hydr- "water" and -gène "producer"; so called because when hydrogen gas burns, it combines with oxygen to produce water

Medical Definition

hydrogen

noun

hy·​dro·​gen ˈhī-drə-jən 

: a nonmetallic element that is the simplest and lightest of the elements and that is normally a colorless odorless highly flammable diatomic gas

—symbol H see deuterium, tritium Chemical Elements Table

hydrogenous

hī-ˈdräj-ə-nəs 

adjective