| Adj. | 1. | fissile - capable of undergoing nuclear fission; "a fissionable nucleous"; "fissionable material" natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" |
| 2. | fissile - capable of being split or cleft or divided in the direction of the grain; "fissile crystals"; "fissile wood" nonfissile - not fissile |