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thallium

[ thal-ee-uhm ]
/ ˈθæl i əm /
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noun Chemistry.

a soft, malleable, rare, bluish-white metallic element: used in the manufacture of alloys and, in the form of its salts, in rodenticides. Symbol: Tl; atomic weight: 204.37; atomic number: 81; specific gravity: 11.85 at 20°C.

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Origin of thallium

1860–65; <New Latin, equivalent to thall- (<Greek thallós green stalk) + -ium-ium; named after green line in its spectrum
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

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British Dictionary definitions for thallium

thallium
/ (ˈθælɪəm) /

noun

a soft malleable highly toxic white metallic element used as a rodent and insect poison and in low-melting glass. Its compounds are used as infrared detectors and in photoelectric cells. Symbol: Tl; atomic no: 81; atomic wt: 204.3833; valency: 1 or 3; relative density: 11.85; melting pt: 304°C; boiling pt: 1473±10°C

Word Origin for thallium

C19: from New Latin, from Greek thallos a green shoot; referring to the green line in its spectrum
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 thallium

thallium
[ thălē-əm ]

n. Symbol Tl

A soft, malleable, highly toxic metallic element whose radioisotopes are used in diagnostic imaging. Atomic number 81.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for thallium

thallium
[ thălē-əm ]

Tl

A soft, malleable, very poisonous metallic element that is used in photography, in making low-melting and highly refractive glass, and in treating skin infections. Atomic number 81; atomic weight 204.38; melting point 303.5°C; boiling point 1,457°C; specific gravity 11.85; valence 1, 3. See Periodic Table.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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