English
fissionable
From fission + -able.
A compound of fission + -able
Proto-Indo-European *bʰeyd- ‘to split’
…
Proto-Italic *findō ‘to split, cleave’
Latin findō ‘split, divide’
Latin fissiō ‘the act of breaking up’
Latin fissiōnem
English fission
Today it means
adj Capable of undergoing nuclear fission; fissile.
Language periods are conventional ranges, not dates for this word.
Etymograph / fissionable