thorium
[ thawr-ee-uh m, thohr- ]
/ ˈθɔr i əm, ˈθoʊr- /
noun Chemistry.
a grayish-white, lustrous, somewhat ductile and malleable, radioactive metallic element present in monazite: used as a source of nuclear energy, as a coating on sun-lamp and vacuum-tube filament coatings, and in alloys. Symbol: Th; atomic weight: 232.038; atomic number: 90; specific gravity: 11.7.
Compare
thoria.
OTHER WORDS FROM thorium
thor·ic [thawr-ik, thor-] /ˈθɔr ɪk, ˈθɒr-/, adjectiveWords nearby thorium
Example sentences from the Web for thorium
British Dictionary definitions for thorium
thorium
/ (ˈθɔːrɪəm) /
noun
a soft ductile silvery-white metallic element. It is radioactive and occurs in thorite and monazite: used in gas mantles, magnesium alloys, electronic equipment, and as a nuclear power source. Symbol: Th; atomic no: 90; atomic wt: 232.0381; half-life of most stable isotope, 232 Th: 1.41 × 10 10 years; valency: 4; relative density: 11.72; melting pt: 1755°C; boiling pt: 4788°C
Derived forms of thorium
thoric, adjectiveWord Origin for thorium
C19: New Latin, from
Thor +
-ium
Medical definitions for thorium
thorium
[ thôr′ē-əm ]
n. Symbol Th
A radioactive metallic element that is used in magnesium alloys; its longest-lived isotope, Th 232, has a half-life of 1.41 X 1010 years. Atomic number 90.
Scientific definitions for thorium
thorium
[ thôr′ē-əm ]
Th
A silvery-white, radioactive metallic element of the actinide series. It is used for fuel in some nuclear reactors and for improving the high-temperature strength of magnesium alloys. The only naturally occurring isotope of thorium, Th 232, is also its most stable, having a half-life of 14.1 billion years. Atomic number 90; atomic weight 232.038; approximate melting point 1,750°C; approximate boiling point 4,500°C; approximate specific gravity 11.7; valence 4. See Periodic Table.