from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A radioactive metallic element, occurring naturally in small quantities as a product of radium disintegration and produced synthetically by bombarding bismuth or lead with neutrons. Most isotopes decay by alpha-particle emission; the most stable are Po-208 and Po-209, with half-lives of 2.9 years and 102 years, respectively. Po-210, with a half-life of 138.4 days, is the most readily available isotope and is extremely toxic. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.20; valence 2, 4, 6. cross-reference: Periodic Table.

from The Century Dictionary.

  • noun A radioactive substance discovered in pitchblende by M. and Mme. Curie in 1898: named in honor of Poland, the native country Of Mme. Curie.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Chem.) A radioactive chemical element, discovered by M. and MMe. Curie in pitchblende, and originally called radium F. It has atomic number 84 and an atomic weight of 210. It is a very rare natural element, having an abundance in uranium ores only 0.2% that of radium. It is closely related chemically to bismuth. It emits only alpha rays, and has a half-life of 138 days. It is thus more unstable than radium, and a milligram of polonium emits as many alpha particles as 5 grams of radium. Twenty-seven isotopes are known, with atomic masses from 192 to 218. At present a more practical method of preparation than isolation from ores is the preparation by neutron bombardment of bismuth in a nuclear reactor, and it may be obtained commercially by users having an appropriate permit.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun a chemical element (symbol Po) with atomic number 84.

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

  • noun a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor


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

[From Medieval Latin Polōnia, Poland (the native country of Pierre and Marie Curie, the element's discoverers).]

from Wiktionary, Creative Commons Attribution/Share-Alike License

New Latin Polonia ("Poland")


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  • Po.

    December 16, 2007

  • Polonium rays

    March 5, 2012

  • Polonium is a radioactive poison, a slow killer with no cure. One gram of vaporized polonium can kill about 1.5 million people in just a couple of months. The most famous case of polonium poisoning is that of ex-Russian spy Alexander Litvinenko. Polonium was found in his tea cup, a dose 200 times higher than the median lethal dose in case of ingestion. He died in three weeks.

    February 27, 2015