| fissile šekâftpazir (#), šekâftani (#) Fr.: fissile    Any material that is capable of undergoing → nuclear fission by → thermal neutrons. The three primary fissile materials are uranium-233, uranium-235, and plutonium-239. Although sometimes used as a synonym for → fissionable material, this term has acquired a more restricted meaning. From L. fissilis, from fiss(us), + -illis a suffix of adjectives expressing capability, susceptibility, liability, aptitude, etc. Šekâftani, from šekâft, → fission + -i a suffix expressing capability, aptitude, etc. | 
| fissile isotope izotop-e šektpazir Fr.: isotope fissile    An isotope that is capable of undergoing nuclear fission after capturing either fast neutron or thermal neutron. Typical fissionable isotopes: 238U, 240Pu, but also 235U, 233U, 239Pu, 241Pu |