An example of rare earth is cerium, a chemical oxidizing agent, that provides the yellow color in glass and acts as a catalyst for self-cleaning ovens.
- any of certain basic oxides much alike in physical and chemical properties; specif., any of the oxides of the rare-earth elements
- any of the rare-earth elements
- Any of various oxides of the rare-earth elements.
- A rare-earth element.
Origin of rare earthrare1 (because the minerals from which the rare-earth elements were first isolated are uncommon) + earth, metallic oxide.