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[fur-mee; Italian fer-mee]
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noun Physics.
  1. a unit of length, 10−15 m, used in measuring nuclear distances. Symbol: F

Origin of fermi

named after E. Fermi
Also called femtometer.


[fur-mee; Italian fer-mee]
  1. En·ri·co [en-ree-koh; Italian en-ree-kaw] /ɛnˈri koʊ; Italian ɛnˈri kɔ/, 1901–54, Italian physicist, in the U.S. after 1939: Nobel Prize 1938.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for fermi


  1. a unit of length used in nuclear physics equal to 10 –15 metre

Word Origin

C20: named after Enrico Fermi


  1. Enrico (enˈriːko). 1901-54, Italian nuclear physicist, in the US from 1939. He was awarded a Nobel prize for physics in 1938 for his work on radioactive substances and nuclear bombardment and headed the group that produced the first controlled nuclear reaction (1942)
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

fermi in Science


  1. Italian-born American physicist who won a 1938 Nobel Prize for his research on neutrons. In 1942, with Leo Szilard, Fermi built the world's first nuclear reactor. He also discovered over 40 new isotopes, including the element fermium, which is named for him.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.