helium
/ˈhiːlɪəm
/noun [mass noun]
The chemical element of atomic number 2, an inert gas which is the lightest member of the noble gas series. (Symbol: He) 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.
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 hydrogen.
Origin
Late 19th century: modern Latin, from Greek hēlios 'sun', because its existence was inferred from an emission line in the sun's spectrum.
Rhymes
- cross-rate
- cross-reaction
- cross-refer
- cross reference
- cross-rhythm
- crossroads
- cross-ruff
- cross section
- cross-sectional
- cross-sectoral
- cross-sell
- cross-slide
- cross someone's palm with silver
- cross someone's path
- cross-stitch
- cross street
- cross-subsidise
- cross-subsidization
- cross-subsidize
- cross-subsidy
- cross swords
- crosstalk
- cross that bridge when one comes to it
- cross the floor
- cross the T