helium

noun2

1. •
   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
2. •
   A form or sample of the element.