from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A naturally radioactive metallic element, occurring in minute quantities as a product of radium disintegration and produced by bombarding bismuth or lead with neutrons. It has 27 isotopes ranging in mass number from 192 to 218, of which Po 210, with a half-life of 138.39 days, is the most readily available. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.32; valence 2, 4. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a chemical element (symbol Po) with atomic number 84.
from the GNU version of the Collaborative International Dictionary of English
- n. 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 The Century Dictionary and Cyclopedia
- n. 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 WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. 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 Medieval Latin Polōnia, Poland (the native country of Pierre and Marie Curie, the element's discoverers).(American Heritage® Dictionary of the English Language, Fourth Edition)
New Latin Polonia ("Poland") (Wiktionary)