rare earthWiktionary 原文英美构词拆解rare词干+earth词干词源说明From rare + earth. First use appears c. 1841 in the publications of Henry Minchin Noad. See cite below.释义名词noun1(chemistry) Any of the naturally occurring oxides of the lanthanide metals; they are widely distributed in relatively small concentrations and are used in glassmaking, ceramic glazes etc.