: 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
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Building a Treasure Map Helium-3 is an isotope of helium that possesses one fewer neutron than its run-of-the-mill counterpart, helium-4, which is the only other stable helium isotope.
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Robin George Andrews, Scientific American, 14 May 2026
After being tested for airtightness, helium was pumped into the glass enclosure through thin tubes inserted into the lead lining, to protect the document from corrosive oxygen and parasites.
—Literary Hub, 13 May 2026
The landlocked nation could possibly even collect the helium, which is in high demand and has several applications in medicine and the tech industry.
—Jacopo Prisco, CNN Money, 13 May 2026
The older generation, found in the halo of our galaxy, are Population II stars, which have far lower levels of elements heavier than helium.
—Jacek Krywko, ArsTechnica, 13 May 2026
See All Example Sentences for helium
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Robin George Andrews, Scientific American, 14 May 2026
After being tested for airtightness, helium was pumped into the glass enclosure through thin tubes inserted into the lead lining, to protect the document from corrosive oxygen and parasites.
—Literary Hub, 13 May 2026
The landlocked nation could possibly even collect the helium, which is in high demand and has several applications in medicine and the tech industry.
—Jacopo Prisco, CNN Money, 13 May 2026
The older generation, found in the halo of our galaxy, are Population II stars, which have far lower levels of elements heavier than helium.
—Jacek Krywko, ArsTechnica, 13 May 2026
See All Example Sentences for helium
Cite this Entry
“Helium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/helium. Accessed 16 May. 2026.
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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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