di·dym·i·um /daɪˈdɪmiəm/
  一種化學混合物
  Di·dym·i·um n.  Chem. A rare metallic substance usually associated with the metal cerium; -- hence its name. It was formerly supposed to be an element, but has since been found to consist of two simpler elementary substances, neodymium and praseodymium. See Neodymium, and Praseodymium.
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