What does fissionable mean?
Fissionable means capable of undergoing fission, particularly the splitting of an atomic nucleus into smaller nuclei, usually with the release of energy. The term is most common in nuclear physics, reactor technology, and the history of atomic weapons. It is especially associated with materials, isotopes, and nuclei that can sustain a chain reaction. In everyday discussion, fissionable may also be understood more broadly as able to be divided or split, although its primary meaning is technical and nuclear. The adjective is closely related to fissile, but fissile has the more specific sense of describing a substance that can undergo fission after absorbing a neutron. Fissionable is therefore a useful word for identifying the essential property behind nuclear energy and the many political and scientific debates surrounding it.
adjectiveCapable of undergoing fission, especially nuclear fission; able to be split into smaller components.
- Capable of undergoing fission, especially the splitting of an atomic nucleus into smaller nuclei and released energy.
"The reactor was designed to use only fissionable material under strict safety controls."
"Only a small quantity of fissionable material is required to initiate a chain reaction."
"The report explained why the newly discovered isotope was considered particularly fissionable."
Fissionable describes the property that made nuclear power possible—and the central concern of the atomic age.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does fissionable come from?
Fissionable was formed in the 19th century from fission and the suffix -able, meaning “capable of undergoing” the process denoted by the root. Fission comes through French from Latin fissio, a splitting, ultimately associated with findere, “to split.” Related English words include fissile, fissility, and fissuration, all reflecting the same concept of division or splitting.
Related word forms
How fissionable is actually used
Fissionable is formal and technical, especially in nuclear physics and weapons-related discussion. It is sometimes used broadly in place of fissile, but the latter has a narrower meaning in nuclear engineering.
Easily confused with fissionable
Fissionable generally means capable of undergoing fission, while fissile is a more specific nuclear-physics term for material that can undergo fission after absorbing a neutron.