helium

Etymology

From New Latin helium, from Ancient Greek ἥλιος (hḗlios, “sun”) (because its presence was first theorised in the Sun's atmosphere) with the suffix + -ium.

noun

1. (uncountable) The second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.
   It was an enormous balloon filled with helium, that elemental gas forged from hydrogen in the nuclear furnace of the stars. 1997, Ian McEwan, Enduring Love, Vintage (1998), page 3
2. (countable) A form or sample of the element.