fast reactor fast-plighted • fast-rooted · · · Info · Definitions · Antonyms · Characters · · fast reactor · · Text Common · · Latin · · Scripts 12 · · Length 4 · · Syllables Definitions · · · (noun) nuclear reactor in which nuclear fissions are caused by fast neutrons because little or no moderator is used. Synonyms: fast reactor. · · Noun Definition 1 Antonyms · · · thermal reactor · · Antonym 0 Characters · · space U+0020 a latin small letter a U+0061 c latin small letter c U+0063 e latin small letter e U+0065 f latin small letter f U+0066 o latin small letter o U+006F r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074