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barium

American  
[bair-ee-uhm, bar-] / ˈbɛər i əm, ˈbær- /

noun

Chemistry.

  1. a whitish, malleable, active, divalent, metallic element, occurring in combination chiefly as barite or as witherite. Ba; 137.34; 56; 3.5 at 20°C.

barium British  
/ ˈbɛərɪəm /

noun

  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

"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
barium Scientific  
/ bâr′ē-əm /

  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.

  2. See Periodic Table

Etymology

Origin of barium

First recorded in 1800–10; bar(ytes) + -ium

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

These are four endoscopy tests - upper endoscopy; lower endoscopy excluding colonoscopy; colonoscopy; and cystoscopy - and four radiology tests - CT scan; MRI scan; barium studies; and non-obstetric ultrasound.

From BBC • Nov. 25, 2025

Its nonlinear optical response was 20 times greater than that of lithium niobate, the leading nonlinear optical material, and nearly triple that of barium titanate, the previous cryogenic benchmark.

From Science Daily • Nov. 9, 2025

The Environmental Protection Agency does not consider it a carcinogen; however, exposure to barium can cause gastrointestinal irritation, cardiovascular effects, kidney damage and respiratory problems.

From Los Angeles Times • May 4, 2025

Compounds containing barium, aluminum, silicon and cobalt were ground together, pressed into a sheet, then heated to above 2550 degrees Fahrenheit to form the pigment.

From Science Daily • Feb. 22, 2024

She was given an endoscopy, an MRI, and a barium swallow to test her gastrointestinal tract.

From "Zeitoun" by Dave Eggers

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.