from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A whitish, largely inert gaseous element used chiefly in gas discharge lamps and fluorescent lamps. Atomic number 36; atomic weight 83.80; melting point -156.6°C; boiling point -152.30°C; density 3.73 grams per liter (0°C). See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A chemical element (symbol Kr) with an atomic number of 36; one of the noble gases.

from the GNU version of the Collaborative International Dictionary of English

  • n. An inert gaseous element of the argon (noble gas) group, of atomic number 36, occurring in air to the extent of about one volume in a million. It was discovered by Ramsay and Travers in 1898. Boiling point, -152.3° C.; melting point, -156.6° C.; symbol, Kr; atomic weight, 83.8.

from The Century Dictionary and Cyclopedia

  • n. A chemical element, one of the five recently discovered gaseous constituents of the atmosphere, first obtained by Ramsay and Travers in 1898.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a colorless element that is one of the six inert gasses; occurs in trace amounts in air


Greek krupton, neuter of kruptos, hidden (from its rarity), from kruptein, to hide.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Neuter form of Ancient Greek κρυπτός ("hidden"). (Wiktionary)



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  • Kr.

    December 16, 2007

  • Can be spelled with the Periodic Table of Elements symbols: KrYPtON

    December 12, 2006