| lutetium |
a metal chemical element of the rare-earth group that has seventy-one protons in each nucleus. (symbol: Lu) |
| monazite |
a yellow-brown or red-brown mineral phosphate of rare-earth metals that is a major source of thorium, cerium, and the like. |
| neodymium |
a rare-earth metallic chemical element that has sixty protons in each nucleus and that occurs most frequently as a trivalent ion in salts and minerals, used esp. in coloring high-quality optical glass. (symbol: Nd) |
| out-of-the-way |
unusual or rare. [1/3 definitions] |
| pegmatite |
a coarse, grainy granite that occurs in layers and sometimes contains rare metals such as uranium. |
| phenomenon |
an unusual or rare occurrence or fact, often one that cannot be explained; marvel. [1/3 definitions] |
| praseodymium |
a rare-earth metallic chemical element that has fifty-nine protons in each nucleus and that is usu. found together with neodymium. (symbol: Pr) |
| promethium |
a synthetic radioactive chemical element of the rare-earth metallic group that has sixty-one protons in each nucleus. (symbol: Pm) |
| rara avis |
(Latin) rare bird; a rare, special, or unique person or thing. |
| rare earth |
any oxide of a rare-earth metal. [2 definitions] |
| rarity |
something that is rare or unusual. [2/4 definitions] |
| recherché |
very unusual, rare, or refined. [1/3 definitions] |
| Reye's syndrome |
a rare, acute, often fatal disease that chiefly affects children, usu. follows a viral disease, and is characterized by fever, vomiting, enlargement of the brain and liver, and neurological disorders. |
| rhebok |
a rare, brownish gray antelope that lives on the rocky hillsides of South Africa. |
| samarium |
a rare-earth metal chemical element that has sixty-two protons in each nucleus and that forms a permanent magnet when alloyed with cobalt. (symbol: Sm) |
| samarskite |
a deep black mineral with reddish brown streaks that contains some rare-earth metals and traces of oxides of uranium, thorium, and the like. |
| supernova |
a rare and very bright object that results from the explosion of a star. |
| terbium |
a rare-earth chemical element that has sixty-five protons in each nucleus and that occurs in pure form as a soft silvery metal. (symbol: Tb) |
| thulium |
a rare-earth chemical element that has sixty-nine protons in each nucleus and that occurs as a malleable solid metal. (symbol: Tm) |
| uncommon |
unusual or rare. [1/2 definitions] |
| whooping crane |
a large North American bird, now rare, that has black and white plumage and a loud, whooping call. |