| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
| the offspring of a zebra and a donkey. |
uranium u·ra·ni·um (y&oobreve;-rā'nē-əm)
n.
Symbol U
An easily oxidized radioactive toxic metallic element having 16 known isotopes, of which U 238 is the most naturally abundant. Atomic number 92; atomic weight 238.03; melting point 1,135°C; boiling point 4,151°C; specific gravity 18.95; valence 2, 3, 4, 5, 6.
uranium (y -rā'nē-əm) Pronunciation Key
Symbol U A heavy, silvery-white, highly toxic, radioactive metallic element of the actinide series. It has 14 known isotopes, of which U 238 is the most naturally abundant, occurring in several minerals. Fissionable isotopes, especially U 235, are used in nuclear reactors and nuclear weapons. Atomic number 92; atomic weight 238.03; melting point 1,132°C; boiling point 3,818°C; specific gravity 18.95; valence 2, 3, 4, 5, 6. See Periodic Table. |
A chemical element that is naturally radioactive. An isotope of uranium, uranium 235, is the main fuel for nuclear reactors and atomic bombs. Its symbol is U. (See fission and chain reaction.)