- The chemical element of atomic number 2, an inert gas that is the lightest member of the noble gas series. (Symbol: He)
Helium occurs in traces in air and more abundantly in natural gas deposits. It is used as a lifting gas for balloons and airships, and liquid helium (boiling point: 4.2 kelvins, 268.9°C) is used as a coolant. Helium is produced in stars as the main product of the thermonuclear fusion of hydrogen and is the second most abundant element in the universe after hydrogenMore example sentences
- Other light elements that are commonly proposed for the outer core are silicon, carbon, helium, and nitrogen.
- Ramsay realized that argon and helium might be members of a hitherto unsuspected new group in the Periodic Table.
- Cool the detectors with liquid nitrogen instead of solid hydrogen or liquid helium.
late 19th century: modern Latin, from Greek hēlios 'sun', because its existence was inferred from an emission line in the sun's spectrum.
More definitions of heliumDefinition of helium in:
- The British & World English dictionary