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[fur-mee-uh m] /ˈfɜr mi əm/
noun, Chemistry, Physics.
a transuranic element. Symbol: Fm; atomic number: 100.
1950-55; named after E. Fermi; see -ium Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for fermium
  • The elements curium, einsteinium, and fermium were named after famous nuclear physicists.
  • The chemical properties of fermium have been studied solely with tracer amounts.
British Dictionary definitions for fermium


a transuranic element artificially produced by neutron bombardment of plutonium. Symbol: Fm; atomic no: 100; half-life of most stable isotope, 257Fm: 80 days (approx.)
Word Origin
C20: named after Enrico Fermi
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for fermium



discovered in the debris of a 1952 U.S. nuclear test in the Pacific, named 1955 for Italian-born U.S. physicist Enrico Fermi (1901-1954).

Online Etymology Dictionary, © 2010 Douglas Harper
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fermium in Medicine

fermium fer·mi·um (fûr'mē-əm, fěr'-)
Symbol Fm
A synthetic radioactive metallic element whose most stable isotope is Fm 257 with a half-life of [approx] 100 days. Atomic number 100.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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fermium in Science
Symbol Fm
A synthetic, radioactive metallic element of the actinide series that is produced from plutonium or uranium. Its most stable isotope is Fm 257 with a half-life of approximately 100 days. Atomic number 100. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for fermium


(Fm), synthetic chemical element of the actinoid series of the periodic table, atomic number 100. Fermium (as the isotope fermium-255) is produced by the intense neutron irradiation of uranium-238 and was first positively identified by Albert Ghiorso and coworkers at Berkeley, Calif., in debris taken from the first thermonuclear or hydrogen-bomb test explosion (November 1952), in the South Pacific. All fermium isotopes are radioactive. Mixtures of the isotopes fermium-254 (3.24-hour half-life), fermium-255 (20.1-hour half-life), fermium-256 (2.7-hour half-life), and fermium-257 (80-day half-life) can be produced by the intensive slow-neutron irradiation of elements of lower atomic number, such as plutonium.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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