: 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
It was understood that a pressurized helium tank inside the upper stage had ruptured.
—
ArsTechnica, 5 May 2025
This can get very complicated, but some massive stars can then fuse that helium into heavier elements and those elements into heavier ones yet.
—Phil Plait, Scientific American, 10 Apr. 2025
The exoplanets as puffy as cotton candy Super-puff planets have tiny cores and thick gassy coats of hydrogen or helium, such that their overall density is as light as cotton candy.
—Shi En Kim, Smithsonian Magazine, 1 Apr. 2025
There were just giant clouds of pristine hydrogen and helium floating around, on their slow-and-steady way to becoming the rich tapestry of the modern-day cosmos.
—Paul Sutter, Space.com, 21 Apr. 2025
See All Example Sentences for helium
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ArsTechnica, 5 May 2025
This can get very complicated, but some massive stars can then fuse that helium into heavier elements and those elements into heavier ones yet.
—Phil Plait, Scientific American, 10 Apr. 2025
The exoplanets as puffy as cotton candy Super-puff planets have tiny cores and thick gassy coats of hydrogen or helium, such that their overall density is as light as cotton candy.
—Shi En Kim, Smithsonian Magazine, 1 Apr. 2025
There were just giant clouds of pristine hydrogen and helium floating around, on their slow-and-steady way to becoming the rich tapestry of the modern-day cosmos.
—Paul Sutter, Space.com, 21 Apr. 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 19 May. 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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