fem·​to·​me·​ter | \ ˈfem(p)-tə-ˌmē-tər How to pronounce femtometer (audio) , -tō- \

Definition of femtometer

: a unit of length equal to 10−15 meters : one quadrillionth of a meter

Examples of femtometer in a Sentence

Recent Examples on the Web This explains why the proton and neutron have particular sizes to them, where each one has a radius that’s a little smaller than a femtometer. Ethan Siegel, Forbes, 20 Apr. 2021 Finally, the results are in: Hessels and company have pegged the proton’s radius at 0.833 femtometers, give or take 0.01, a measurement exactly consistent with Pohl’s value. Quanta Magazine, 11 Sep. 2019 Pohl and his team were surprised to find a lower value for the radius, pegging it at 0.84 femtometer—well outside the range of potential sizes established by earlier measurements. Dan Falk, Scientific American, 28 Nov. 2019 The result: their measurement of 0.833 femtometers (just under one-trillionth of a meter) agrees with the smaller value from the 2010 study. Jennifer Ouellette, Ars Technica, 5 Sep. 2019

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

First Known Use of femtometer

1971, in the meaning defined above

History and Etymology for femtometer

femto- + meter entry 3

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The first known use of femtometer was in 1971

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Cite this Entry

“Femtometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/femtometer. Accessed 1 Jul. 2022.

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