: a chemical element of the noble gas group with atomic number 2 that is found especially in natural gases and used chiefly for inflating airships and balloons, as a coolant for superconductors, and as a component of inert atmospheres (as in welding)
—often used before another noun
helium balloons
helium gas
see Chemical Elements Table
Examples of helium in a Sentence
Recent Examples on the Web
These included a faulty valve on the Atlas V rocket's upper stage, and then a helium leak inside Boeing's Starliner spacecraft.
—
ArsTechnica, 1 Apr. 2025
Wilmore and Williams returned to Earth after being stuck in space since June, due to engineers discovering helium leaks and issues involving thrusters shortly after Boeing’s CST-100 Starliner docked with the International Space Station.
—Greg Wehner, FOXNews.com, 31 Mar. 2025
Teams will also continue to test new seal options for the helium system, in an effort to minimize the risks of leaks going forward.
—Mike Wall, Space.com, 28 Mar. 2025
By comparing the X-ray data with computer models of stellar explosions, the team concluded that the original star was about 25 times the mass of the sun and was much richer in elements heavier than helium in comparison with the sun.
—Ron Estes, MSNBC Newsweek, 28 Mar. 2025
See All Example Sentences for helium
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ArsTechnica, 1 Apr. 2025
Wilmore and Williams returned to Earth after being stuck in space since June, due to engineers discovering helium leaks and issues involving thrusters shortly after Boeing’s CST-100 Starliner docked with the International Space Station.
—Greg Wehner, FOXNews.com, 31 Mar. 2025
Teams will also continue to test new seal options for the helium system, in an effort to minimize the risks of leaks going forward.
—Mike Wall, Space.com, 28 Mar. 2025
By comparing the X-ray data with computer models of stellar explosions, the team concluded that the original star was about 25 times the mass of the sun and was much richer in elements heavier than helium in comparison with the sun.
—Ron Estes, MSNBC Newsweek, 28 Mar. 2025
See All Example Sentences for helium
Cite this Entry
“Helium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/helium. Accessed 14 Apr. 2025.
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Medical Definition
helium
noun
he·li·um
ˈhē-lē-əm 
: a light colorless nonflammable gaseous element found especially in natural gases and used chiefly for inflating airships and balloons, for filling incandescent lamps, and for cryogenic research
—symbol He
see Chemical Elements Table
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