| NOUN | substance | rare earth, rare-earth element, lanthanoid, lanthanide, lanthanon | any element of the lanthanide series (atomic numbers 57 through 71) |
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| Meaning | Any element of the lanthanide series (atomic numbers 57 through 71). | |
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| Synonyms | rare-earth element, lanthanoid, lanthanide, lanthanon | |
| Narrower | terbium metal | A separate group of related lanthanides, including terbium, europium, gadolinium, and sometimes dysprosium |
| Broader | group, grouping | Any number of entities (members) considered as a unit |