> as lemmas
non-fissionable
non-fissionable adj. 
/(ˌ)nɒnˈfɪʃənəbl/, /ˌnɑnˈfɪʒ(ə)nəb(ə)l/
Brit. /(ˌ)nɒnˈfɪʃn̩əbl/
, /(ˌ)nɒnˈfɪʃn̩əbl//(ˌ)nɒnˈfɪʃənəbl/U.S. /ˌnɑnˈfɪʃ(ə)nəb(ə)l/
, /ˌnɑnˈfɪʃ(ə)nəb(ə)l//ˌnɑnˈfɪʒ(ə)nəb(ə)l/ΚΠ
1946 Science 14 June 699/2 Radioactive isotopes are created in chain-reacting piles by..the fission of U 235 nuclei.., and..neutron absorption by nonfissionable nuclei.
1992 N.Y. Rev. Bks. 17 Dec. 35/2 Feynman collaborated with Paul Olum and Robert Wilson on a device for culling the fissionable form of uranium from the nonfissionable.
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