- A colorless, odorless, noble gas element found in minute quantities in the atmosphere, extracted commercially from liquefied air and used in stroboscopic, bactericidal, and laser-pumping lamps. Atomic number 54; atomic weight 131.29; melting point −111.74°C; boiling point −108.09°C; density (gas) 5.89 grams per liter; specific gravity (liquid, at −109°C) 2.95; valence 0, 2, 4, 6. <i>cross-reference</i>: <strong> Periodic Table</strong>.
- In <em>chem.</em>, the heaviest of the five recently discovered elementary substances present in gaseous form in the atmosphere.
- 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° C., and to a solid which melts at -111.9° C. Symbol Xe (formely also X); atomic number 54; atomic weight 131.3.
- A heavy, gaseous chemical element (symbol Xe) of the noble gases group with an <xref>atomic number</xref> of 54.
- a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts