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

  • n. A radioactive, inert, gaseous isotope of radon, with a half-life of 3.92 seconds.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Any of the radioactive isotopes of radon
  • n. Any radioactive isotope of an actinide

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

  • n. any of a series of radioactive elements with atomic numbers 89 through 103


actin(ium) + -on2.
(American Heritage® Dictionary of the English Language, Fourth Edition)


  • The combat actinon in which Berg was lost is described in the last chapter of John L. Plaster's new book SOG: The Secret Wars of America's Commandos in

    Berg, Bruce A.

  • I think a class actinon law suit will open there eyes.



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