The Collaborative International Dictionary of English v.0.48:

Noble \No"ble\, a. [Compar. Nobler; superl. Noblest.] [F.
   noble, fr. L. nobilis that can be or is known, well known,
   famous, highborn, noble, fr. noscere to know. See know.]
   1. Possessing eminence, elevation, dignity, etc.; above
      whatever is low, mean, degrading, or dishonorable;
      magnanimous; as, a noble nature or action; a noble heart.
      [1913 Webster]

            Statues, with winding ivy crowned, belong
            To nobler poets for a nobler song.    --Dryden.
      [1913 Webster]

   2. Grand; stately; magnificent; splendid; as, a noble
      edifice.
      [1913 Webster]

   3. Of exalted rank; of or pertaining to the nobility;
      distinguished from the masses by birth, station, or title;
      highborn; as, noble blood; a noble personage.
      [1913 Webster]

   Note: Noble is used in the formation of self-explaining
         compounds; as, noble-born, noble-hearted, noble-minded.
         [1913 Webster]

   Noble gas (Chem.), a gaseous element belonging to group
      VIII of the periodic table of elements, not combining with
      other elements under normal reaction conditions;
      specifically, helium, neon, argon, krypton,
      xenon, or radon; also called inert gas.

   Noble metals (Chem.), silver, gold, and platinum; -- so
      called from their resistance to oxidation by air and to
      dissolution by acids. Copper, mercury, aluminium,
      palladium, rhodium, iridium, and osmium are sometimes
      included.
      [1913 Webster]

   Syn: Honorable; worthy; dignified; elevated; exalted;
        superior; sublime; great; eminent; illustrious;
        renowned; stately; splendid; magnificent; grand;
        magnanimous; generous; liberal; free.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Xenon \Xen"on\ (z[e^]n"[o^]n; z[=e]"n[o^]n), n. [Gr. xe`non,
   neut. of xe`nos strange.] (Chem.)
   A very heavy, inert gaseous element of the noble gas group,
   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 -107[deg]
   C., and to a solid which melts at -111.9[deg] C. Symbol Xe
   (formerly also X); atomic number 54; atomic weight 131.3.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

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

The Elements (07Nov00):

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.