| actinium |
a radioactive chemical element of the rare-earth group that has eighty-nine protons in each nucleus. (symbol: Ac) |
| antiquarian |
of, relating to, or dealing in rare old books. [1/3 definitions] |
| ball lightning |
a rare form of lightning manifested in the form of a glowing reddish ball, approximately six inches to a foot in diameter, that moves rapidly along the ground or in the air until it disintegrates. |
| bibliomania |
a craze for acquiring and owning books, esp. rare books. |
| bibliophile |
a lover or collector of books, esp. for the fine or rare physical qualities of their paper, printing, binding, or the like. |
| bibliopole |
a bookseller, esp. of rare books. |
| botanical garden |
a garden in which many species of plants, esp. exotic or rare specimens, are displayed for enjoyment and scientific study. |
| cerium |
a highly reactive chemical element of the rare-earth group that has fifty-eight protons in each nucleus and that occurs naturally only in compounds. (symbol: Ce) |
| collector's item |
an object that might have especial value or interest for a collector, usu. because it is rare or unusual. |
| delicacy |
something delightful or rare, esp. food. [1/8 definitions] |
| didymium |
a rare metal, once considered an element, consisting of the elements neodymium and praseodymium. [2 definitions] |
| dysprosium |
a rare-earth metal chemical element of the lanthanide series that has sixty-sixprotons in each nucleus. (symbol: Dy) |
| erbium |
a rare-earth metal chemical element of the lanthanide series that has sixty-eight protons in each nucleus. (symbol: Er) |
| europium |
a highly reactive chemical element of the rare-earth group that has sixty-three protons in each nucleus. (symbol: Eu) |
| exotic |
anything rare or of foreign origin. [1/3 definitions] |
| find |
something found, esp. something rare, valuable, or pleasing. [1/8 definitions] |
| gadolinium |
a metal chemical element of the rare-earth group that has sixty-four protons in each nucleus. (symbol: Gd) |
| holmium |
a chemical element of the rare-earth group that contains sixty-seven protons in each nucleus. (symbol: Ho) |
| lanthanide series |
a series of chemical elements having from fifty-seven to seventy-one protons in each nucleus; rare-earth elements. |
| lanthanum |
a chemical element of the rare-earth group that has fifty-seven protons in each nucleus and that occurs as a soft, highly reactive, solid metal or as a trivalent ion. (symbol: La) |
| lutetium |
a metal chemical element of the rare-earth group that has seventy-one protons in each nucleus. (symbol: Lu) |