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

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Other Words from fissile

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

Did You Know?

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") 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

Most of us won’t be working with fissile materials. Robin Tribble, Popular Mechanics, "The One Thing You Should Never Do with a Screwdriver," 30 Nov. 2018 China's stockpile of fissile materials--plutonium and highly enriched uranium--is only enough for about 250 nuclear weapons. Kyle Mizokami, Popular Mechanics, "Has China Announced a New Long-Range Missile? (Updated)," 24 Jan. 2017 Initial actions could include locking in a freeze on nuclear and missile testing and halting fissile material production. Kelsey Davenport, Time, "This Is What Trump Needs to Do to Make North Korea Get Rid of Their Nukes," 13 June 2018 As for North Korea’s stockpile of fissile material, estimates based on scraps of intelligence have allowed arms-control experts to draw a few rough conclusions. Jonathan Cheng, WSJ, "Step One in Disarming North Korea: Knowing What’s in Kim’s Arsenal," 8 June 2018 The American side would like to all but eliminate fissile material in North Korea. NBC News, "CIA report says North Korea won't denuclearize, but might open a burger joint," 29 May 2018 Those early nuclear reactors allowed North Korea to gain the technical sophistication, as well as a source of fissile material, for its future weapons program. Joby Warrick, Washington Post, "North Korea’s nuclear weapons: What you need to know," 9 Mar. 2018 There are no concrete estimates on the number of nuclear warheads in North Korea, but Kristensen and other analysts agree that Kim Jong Un's regime has produced enough nuclear fissile material to arm and assemble a ballistic missile. Chelsea Bailey, NBC News, "How Many Nuclear Weapons Exist? United Nations Calls for Total Elimination of Nukes," 26 Sep. 2017 If Pyongyang collapsed, refugees and armed North Korean soldiers, fissile material, or even nuclear fallout, could stream over the Yalu and Tumen rivers, which form the border with northeast China, presenting a major challenge to its own stability. Adam Mount, The Atlantic, "How China Sees North Korea," 29 Aug. 2017

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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