fis·​sile | \ ˈfi-səl How to pronounce fissile (audio) , ˈfi-ˌsī(-ə)l \

Definition of fissile

1 : capable of or prone to being split or divided in the direction of the grain or along natural planes of cleavage fissile wood fissile crystals
2 : capable of undergoing fission

Other Words from fissile

fissility \ fi-​ˈsi-​lə-​tē How to pronounce fissile (audio) \ noun

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When scientists first used fissile back in the 1600s, the notion of splitting the nucleus of an atom would have seemed far-fetched indeed. In those days, people thought that atoms were the smallest particles of matter that existed and therefore could not be split. Fissile (which can be traced back to Latin findere, meaning "to split" or "to cleave") was used in reference to things like rocks. When we hear about fissile materials today, the reference is usually to nuclear fission: the splitting of an atomic nucleus that releases a huge amount of energy. But there is still a place in our language for the original sense of fissile (and for the noun fissility, meaning "the quality of being fissile"). A geologist, for example, might refer to slate as being fissile.

Examples of fissile in a Sentence

Recent Examples on the Web This is the ability to put enough pressure on the fissile material to detonate it and create a nuclear yield. CBS News, 5 Jan. 2022 The nation’s output of uranium—a fissile material for nuclear weapons when enriched—is just a fraction of what could be produced, according to new research from Stanford University’s Center for International Security and Cooperation. Timothy W. Martin, WSJ, 4 Nov. 2021 And this means that Iran can distribute this capacity to a place that might be difficult to attack, difficult to discover and would allow Iran to quickly develop the fissile material for a weapon. CBS News, 3 Nov. 2021 Th-232 captures a neutron and converts to U-233 which is also fissile and begins providing more neutrons and more power. James Conca, Forbes, 6 Oct. 2021 The North’s production of fissile materials violates multiple resolutions from the UN Security Council, which has sought to stop the country from developing nuclear warheads, with little success., 30 Aug. 2021 Experts say North Korea has as many as 60 nuclear weapons and produces enough fissile material to add another dozen each year. Steve Chapman,, 21 May 2021 In January, Iran began enriching uranium from the 3.67 concentration allowed under the deal to 20 percent — a step closer to the 90 percent required for the fissile material in a nuclear weapon. Washington Post, 16 Apr. 2021 Yet, Iran hawks argue that Biden should use the Trump-era sanctions to press for a deal that eliminates the regime’s capacity to enrich fissile material. Joel Gehrke, Washington Examiner, 12 Nov. 2020

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

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First Known Use of fissile

1661, in the meaning defined at sense 1

History and Etymology for fissile

borrowed from Latin fissilis "easily split," from fid-, variant stem of findere "to split, cleave" + -tilis "subject to, susceptible to (the action of the verb)" — more at bite entry 1

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The first known use of fissile was in 1661

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Last Updated

9 Jan 2022

Cite this Entry

“Fissile.” Dictionary, Merriam-Webster, Accessed 25 Jan. 2022.

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Nglish: Translation of fissile for Spanish Speakers


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