fissile

adjective

fis·sile ˈfi-səl

ˈfi-ˌsī(-ə)l

: 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

: capable of undergoing fission

fissility

fi-ˈsi-lə-tē

noun

Did you know?

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

Recent Examples on the Web

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

The key characteristic of this posture was the separation of the fissile and non-fissile parts of nuclear weapons, as well as the separation of weapons from their delivery systems. —

Gaurav Kampani, Foreign Affairs, 16 June 2017 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 The new system retains the latter’s ability to burn the widest possible range of fuels — including not just spent nuclear fuel, but also the ordinarily non-fissile uranium-238. —

M. Mitchell Waldrop, Discover Magazine, 26 Feb. 2019 The dirty bomb speculation is tied to comments made by Russian Defense Minister Sergei Shoigu, and repeated last week by Putin, suggesting Ukraine planned to detonate a device loaded with fissile material on its own territory. —

Karoun Demirjian, Washington Post, 2 Nov. 2022 See all Example Sentences for fissile

Word History

Etymology

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

First Known Use

1661, in the meaning defined at sense 1

Time Traveler

The first known use of fissile was in 1661

See more words from the same year