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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
Kevin Breuninger, CNBC, 6 June 2026
Trump has repeatedly said Iran would not receive any sanctions relief until its stockpile of fissile material is removed and destroyed.
—Nabih Bulos, Los Angeles Times, 26 May 2026
Once utilized as fuel, the molten salt is dissolved with fissile material, like uranium-235, plutonium-239 or uranium-233.
—Georgina Jedikovska, Interesting Engineering, 12 May 2026
There’s still fissile material, highly enriched, that was not there at the beginning of his first term.
—NBC news, 10 May 2026
See All Example Sentences for fissile
Cite this Entry
“Fissile.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fissile. Accessed 15 Jun. 2026.
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