xenon
         n 1: a colorless odorless inert gaseous element occurring in the
               earth's atmosphere in trace amounts [syn: {xenon}, {Xe},
               {atomic number 54}]

English Dictionary: xenon	by the DICT Development Group
From Webster's Revised Unabridged Dictionary (1913) [web1913]:
Xenon \Xen"on\, n. [Gr. [?], neut. of [?] strange.] (Chem.)       A very heavy, inert gaseous element occurring in the       atmosphere in the proportion of one volume is about 20       millions. It was discovered by Ramsay and Travers in 1898. It       can be condensed to a liquid boiling at -109[f8] C., and to a       solid which volatilizes without melting. Symbol Xe or X;       atomic weight 130.2.
From The Elements (22Oct97) [elements]:
xenon    Symbol: Xe    Atomic number: 54    Atomic weight: 131.30    Colourless, odourless gas belonging to group 18 on the periodic table (the    noble gases.) Nine natural isotopes and seven radioactive isotopes are    known. Xenon was part of the first noble-gas compound synthesized.    Several others involving Xenon have been found since then. Xenon was    discovered by Ramsey and Travers in 1898.