The Collaborative International Dictionary
nonfissionable
nonfissionable \nonfissionable\ adj. (Physics) not capable of undergoing fission[4]; -- of atoms or chemical elements. Opposite of fissionable.
Wiktionary
nonfissionable
a. Not fissionable.
WordNet
nonfissionable
adj. not capable of undergoing fission [ant: fissionable]
Usage examples of "nonfissionable".
He couldn’t be certain that the planet’s dense atmosphere wouldn’t alter the flight of a nonfissionable missile, so he targeted it directly at an active volcano.