/zee"non, zen"on/ , n. Chem.
a heavy, colorless, chemically inactive, monatomic gaseous element used for filling radio, television, and luminescent tubes. Symbol: Xe; at. wt.: 131.30; at. no.: 54.
[ 1898; xénon, neut. of xénos strange (see -ON 2 ); name introduced by William Ramsay, the element's discoverer ]