thorium

[ thawr-ee-uhm, thohr- ]

/ ˈθɔr i əm, ˈθoʊr- /

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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.

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Compare thoria.

Origin of thorium

<New Latin (1829); see Thor, -ium

OTHER WORDS FROM thorium

thor·ic

[thawr-ik, thor-], /ˈθɔr ɪk, ˈθɒr-/, adjective

Words nearby thorium

Thorez, Thorfinn Karlsefni, thoria, thorianite, thorite, thorium, thorium dioxide, thorium series, thorn, thorn apple, thornback

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

How to use thorium in a sentence

This is a crucial step toward building a thorium nuclear clock.
Nuclear clocks are nearly here|Emily Conover|July 12, 2021|Science News For Students
It measured the energy of other jumps the thorium nucleus can make and subtracted them.
Nuclear clocks are nearly here|Emily Conover|July 12, 2021|Science News For Students
Its abundances of certain heavy elements such as thorium and uranium were higher than would be expected from a neutron star merger.
Souped-up supernovas may produce much of the universe’s heavy elements|Mara Johnson-Groh|July 7, 2021|Science News
A variety of thorium called thorium-229 has a pair of energy levels close enough in energy that a laser could potentially set off the jump.
Nuclear clocks could outdo atomic clocks as the most precise timepieces|Emily Conover|June 4, 2021|Science News

Recent measurements have more precisely pinpointed the energy of that jump, a crucial step toward building a thorium nuclear clock.
Nuclear clocks could outdo atomic clocks as the most precise timepieces|Emily Conover|June 4, 2021|Science News
He was also the person who first identified silicon, selenium, thorium, and serium.
After Dominick|J. J. Berzelius|November 7, 2008|DAILY BEAST
One of my assistants was demonstrating a peculiar property of thorium and Deverill seemed interested.
A Christmas Mystery|William J. Locke
A million bucks of thorium with a hundred years of life in it—have a heart, mister!
The Syndic|C.M. Kornbluth
The precipitate is thorium oxalate, which is washed with hot water, dried, and ignited.
A Textbook of Assaying: For the Use of Those Connected with Mines.|Cornelius Beringer and John Jacob Beringer
Cones of zirconia are also used in the same way; or a thorium mantle in conjunction with alcohol vapour may be employed.
Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 2|Various
However, as we have seen, the view that thorium gives rise to stable lead is beset with some difficulties.
The Birth-Time of the World and Other Scientific Essays|J. (John) Joly

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, adjective

Word Origin for thorium

C19: New Latin, from Thor + -ium

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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 ]

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.