actinide series actinide • actinidia · · · Info · Definitions · Characters · · actinide series · · Text Common · · Latin · · Scripts 15 · · Length 5 · · Syllables Definitions · · · (noun) (chemistry) a series of 15 radioactive elements with increasing atomic numbers from actinium to lawrencium. Synonyms: actinide series. · · Noun Definition 1 Characters · · space U+0020 a latin small letter a U+0061 c latin small letter c U+0063 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 n latin small letter n U+006E r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074