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

The papers detail the structural design, the behavior of the plasma within it, handling of the helium produced by fusion, generation of tritium from the neutrons produced, and obtaining heat from the whole thing. —ArsTechnica, 1 Apr. 2025

Uranus's atmosphere is primarily composed of hydrogen and helium, with a small amount of methane, which gives the planet its characteristic blue-green hue by absorbing red light from the sun and reflecting blue light. —Sharmila Kuthunur, Space.com, 1 Apr. 2025

Despite that intense gravity, a white dwarf can have an atmosphere almost entirely composed of extremely hot hydrogen and helium above its surface. —Phil Plait, Scientific American, 28 Mar. 2025

But scientists suspect that its bloated atmosphere, composed primarily of hydrogen and helium, may be the result of intense heating from its parent star, which the world orbits once every 6.2 days. —Jake Parks, Discover Magazine, 24 Mar. 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