lanthanide noun.
['lanƟǝnʌɪd] E20.[from LANTHANUM + -IDE.]Any of the series of chemical elements having an atomic number between 57 (lanthanum) and 71 (lutetium) inclusive, which form part of the group of transition metals, have similar chemical properties, and occur together in monazite, gadolinite, and certain other minerals. Cf.
rare earth s.v.
RARE adjective1.
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