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helium

(hē′lē əm)

noun

a colorless, odorless chemical element, one of the noble gases, having the lowest known boiling and melting points: it is used in low-temperature work, as a diluent for oxygen, in deep-sea breathing systems, for inflating balloons, etc.: symbol, He; at. no., 2

Origin: ModL < Gr hēlios: see Helios

See helium in American Heritage Dictionary 4

noun Symbol He

A colorless, odorless inert gaseous element occurring in natural gas and with radioactive ores. It is used as a component of artificial atmospheres and laser media, as a refrigerant, as a lifting gas for balloons, and as a superfluid in cryogenic research. Atomic number 2; atomic weight 4.0026; boiling point -268.9°C; density at 0°C 0.1785 gram per liter. See Table at element.

Origin:

Origin: From Greek hēlios, sun (so called because its existence was deduced from the solar spectrum); see sāwel- in Indo-European roots

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