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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
Karishma Vaswani, Twin Cities, 15 Mar. 2026
Similarly, the Arms Control Association estimates Israel has about 90 nuclear warheads, with enough fissile material potentially available for around 200 more weapons.
—Kaif Shaikh, Interesting Engineering, 13 Mar. 2026
As a result, Iran is no longer days or weeks away from securing enough fissile material for a bomb.
—Yarden Segev, NBC news, 9 Mar. 2026
The operation was intended to overturn the theocratic leadership of the country, debilitate Iran’s ballistic missile production and launch capabilities, and shut down the country’s ability to restart enrichment of fissile material that could be used to build a nuclear bomb.
—Brian Bennett, Time, 28 Feb. 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 24 Mar. 2026.
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