platinoid noun 2adjective 1forms 3 noun2 •Any of several metals that resemble platinum in their chemistry, especially osmium, iridium and palladium. •An alloy of copper (60%), zinc (24%), nickel (14%), tungsten (2%), and once used in heating elements.He explained that the wires in modern coils were of a compound called platinoid lately discovered by F. W. Martino. — 1916 adjective1 •Of or resembling platinum. formsplatinoids · more platinoid · most platinoid