Merriam-Webster’s Word of the Day for February 1, 2020 is:
fissile • FISS-ul • adjective
1 : capable of or prone to being split or divided in the direction of the grain or along natural planes of cleavage
2 : capable of undergoing fission
“The facility itself is buried under a mountain. Several hundred feet down, in two cavernous halls, neat rows of centrifuges spin uranium gas to produce fissile isotopes, which could be used for nuclear energy—or, if concentrated enough, a nuclear bomb.” — The Economist, 7 Nov. 2019
“This country that self-identified so smugly as stable, tolerant and moderate, with a crown to symbolise traditions honed down the centuries, is revealed as fissile, fragile and ferociously divided.” — Polly Toynbee, The Guardian (London), 28 Aug. 2019
Did you know?
When scientists first used fissile back in the 1600s, the notion of splitting the nucleus of an atom would have seemed far-fetched indeed. In those days, 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 Latin findere, meaning “to split” or “to cleave”) 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, for example, might refer to slate as being fissile.