fissile

American  

[fis-uhl] / ˈfɪs əl /

adjective

1. capable of being split or divided; cleavable.

2. Physics.

   1. fissionable.

   2. (of a nuclide) capable of undergoing fission induced by low-energy neutrons, as uranium 233 and 235.

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fissile British  

/ ˈfɪsaɪl, fɪˈsɪlɪtɪ /

adjective

1. capable of undergoing nuclear fission as a result of the impact of slow neutrons

2. another word for fissionable

3. tending to split or capable of being split

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Other Word Forms

• fissility noun
• nonfissile adjective
• nonfissility noun
• unfissile adjective

Etymology

Origin of fissile

1655–65; < Latin fissilis, equivalent to fiss ( us ) ( see fissi-) + -ilis -ile

Example Sentences

Both Leavitt and Hegseth, however, mentioned that the United States wants to ensure Iran does not have stockpiles of enriched uranium, the fissile material that is key in developing nuclear weapons.

From Los Angeles Times • Apr. 8, 2026

The Kim regime has an estimated stockpile of roughly 50 nuclear warheads, with the fissile material to produce dozens more.

From The Wall Street Journal • Mar. 15, 2026

Its magic trick is that 0.7% of the element found in nature is fissile.

From Barron's • Dec. 26, 2025

Washington, however, is preparing to conduct next year at the Nevada Test Site two so-called subcritical experiments involving fissile materials in amounts too small to ignite a nuclear explosion.

From Reuters • Oct. 10, 2023

While the Mark I was still undergoing this shakedown procedure, Lawrence spent his time soothing official doubts about the MTA by citing the continuing threat of a shortage of fissile material.

From "Big Science" by Michael Hiltzik