fer·​mi | \ ˈfer-(ˌ)mē How to pronounce fermi (audio) , ˈfər- How to pronounce fermi (audio) \

Definition of fermi

 (Entry 1 of 2)

: a former SI unit of length equal to 10−15 centimeters : femtometer


biographical name
Fer·​mi | \ ˈfer-(ˌ)mē How to pronounce Fermi (audio) \

Definition of Fermi (Entry 2 of 2)

Enrico 1901–1954 American (Italian-born) physicist

Examples of fermi in a Sentence

Recent Examples on the Web: Noun Fermi’s question, apparently raised during a lunch conversation at Los Alamos in the early 1950s, was a simple one: ‘‘ Steven Johnson, New York Times, "Greetings, E.T. (Please Don’t Murder Us.)," 28 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fermi.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of fermi


1955, in the meaning defined above

History and Etymology for fermi


Enrico Fermi

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The first known use of fermi was in 1955

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Cite this Entry

“Fermi.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fermi. Accessed 8 Aug. 2020.

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Rhyming Dictionary: Words that rhyme with fermi

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