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When scientists first used fissile back in the 1600s, the notion of splitting an atom would have seemed far-fetched indeed. At that time, 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 the Latin verb 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 or builder, for example, might describe slate as being fissile, as it splits readily into thin slabs.
Examples of fissile in a Sentence
Micah McCartney, MSNBC Newsweek, 29 Aug. 2025
According to the Stockholm International Peace Research Institute, North Korea has around 50 warheads and has enough fissile material to produce up to 40 more.
—Natasha Lindstaedt, Forbes.com, 28 Aug. 2025
According to the latest estimate from the Stockholm International Peace Research Institute, North Korea has assembled about 50 nuclear warheads and has enough fissile material to produce up to 40 more.
—Jennifer Jett, NBC news, 21 Aug. 2025
One way for North Korea to boost its nuclear stockpile is to ramp up production of lower-yield tactical weapons that require less fissile material.
—Time, 9 Jan. 2023
See All Example Sentences for fissile
Cite this Entry
“Fissile.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fissile. Accessed 10 Sep. 2025.
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