atomic number 64 ato·mic·num·ber uncommon noun 1. a ductile silvery-white ductile ferromagnetic trivalent metallic element of the rare earth group SynonymsgadoliniumGdatomic number 64 Related words Broader terms metallic element Parts gadolinitesamarskite WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
