cerium Cerithium • cermet · · · Info · Definitions · Synonyms · Characters · · cerium · · Text Latin · · Script 6 · · Length Definitions · · · (noun) a ductile grey metallic element of the lanthanide series; used in lighter flints; the most abundant of the rare-earth group. Synonyms: Ce, atomic number 58. · · Noun Definition 1 Synonyms · · · ce · · Synonym 1 atomic number 58 · · Synonym 2 Characters · · c latin small letter c U+0063 e latin small letter e U+0065 i latin small letter i U+0069 m latin small letter m U+006D r latin small letter r U+0072 u latin small letter u U+0075