helium

noun

he·​li·​um ˈhē-lē-əm 

ˈhēl-yəm

: 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

In essence, this would mean that alpha particles (helium nuclei) released by decaying uranium (or some other fissile material) would be focused through engine nozzles to generate thrust. —Matthew S Williams, Interesting Engineering, 10 Jan. 2026

The team spotted helium moving away from the source at around 13 million mph (21 million km/h). —Robert Lea, Space.com, 8 Jan. 2026

Lawmakers are eyeing bills on environmental challenges ranging from the state’s waste crisis, fixing loopholes in existing laws, further restricting helium balloons, and tightening fines for bottle deposit redemption misuse. —Stephen Underwood, Hartford Courant, 2 Jan. 2026

Pure carbon crystals may have floated to the top and got mixed with helium, which would explain the strange atmosphere, Romani said in the release. —Adam Harrington, CBS News, 23 Dec. 2025

Word History

Etymology

New Latin, from Greek hēlios

First Known Use

1871, in the meaning defined above

Rhymes for helium

• cilium

Kids Definition

helium

noun

he·​li·​um ˈhē-lē-əm 

: a light colorless nonflammable element that is found in various natural gases and is used especially to blow up balloons see element

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