• synonyms


[bair-ee-uh m, bar-]
noun Chemistry.
  1. a whitish, malleable, active, divalent, metallic element, occurring in combination chiefly as barite or as witherite. Symbol: Ba; atomic weight: 137.34; atomic number: 56; specific gravity: 3.5 at 20°C.
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Origin of barium

First recorded in 1800–10; bar(ytes) + -ium
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for barium

Historical Examples

  • Will she be able to illuminate a screen treated with platino-cyanide of barium?

    The Shadow World

    Hamlin Garland

  • The chromates of lead and barium separate as yellow precipitates.

  • Oxides of lead, zinc, and barium are often used in this way.

  • What weight of barium sulphate will be formed at the same time?

  • Sulphates, estimated as barium sulphate, and calculated to K2SO4.

British Dictionary definitions for barium


  1. a soft silvery-white metallic element of the alkaline earth group. It is used in bearing alloys and compounds are used as pigments. Symbol: Ba; atomic no: 56; atomic wt: 137.327; valency: 2; relative density: 3.5; melting pt: 729°C; boiling pt: 1805°C
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Word Origin

C19: from bar (yta) + -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

Word Origin and History for barium


1808, coined in Modern Latin by its discoverer, English chemist Sir Humphrey Davy (1778-1829), because it was present in the mineral barytes "heavy spar" (barium sulphate), so named by Lavoisier from Greek barys "heavy" (see grave (adj.)). The metal is actually relatively light.

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Online Etymology Dictionary, © 2010 Douglas Harper

barium in Medicine


(bârē-əm, băr-)
n. Symbol Ba
  1. A soft alkaline-earth metal that is a component in compounds used in radiography and as radiopaque media. Atomic number 56.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

barium in Science


  1. A soft, silvery-white metallic element of the alkaline-earth group. It occurs only in combination with other elements, especially in barite. Barium compounds are used in x-raying the digestive system and in making fireworks and white pigments. Atomic number 56; atomic weight 137.33; melting point 725°C; boiling point 1,140°C; specific gravity 3.50; valence 2. See Periodic Table.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.