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[al-kuh-lahy] /ˈæl kəˌlaɪ/
noun, plural alkalis, alkalies.
  1. any of various bases, the hydroxides of the alkali metals and of ammonium, that neutralize acids to form salts and turn red litmus paper blue.
  2. any of various other more or less active bases, as calcium hydroxide.
  3. (not in technical use) an alkali metal.
  4. Obsolete. any of various other compounds, as the carbonates of sodium and potassium.
Agriculture. a soluble mineral salt or a mixture of soluble salts, present in some soils, especially in arid regions, and detrimental to the growing of most crops.
Chemistry. alkaline.
Origin of alkali
1300-50; Middle English alkaly < Middle French alcali < dialectal Arabic al-qalī, variant of Arabic qily saltwort ashes Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for alkali


noun (pl) -lis, -lies
(chem) a soluble base or a solution of a base
a soluble mineral salt that occurs in arid soils and some natural waters
Word Origin
C14: from Medieval Latin, from Arabic al-qili the ashes (of the plant saltwort)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for alkali

late 14c., "soda ash," from Medieval Latin alkali, from Arabic al-qaliy "the ashes, burnt ashes" (of saltwort, a plant growing in alkaline soils), from qala "to roast in a pan." The modern chemistry sense is from 1813.

Online Etymology Dictionary, © 2010 Douglas Harper
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alkali in Medicine

alkali al·ka·li (āl'kə-lī')
n. pl. al·ka·lis

  1. A carbonate or hydroxide of an alkali metal, the aqueous solution of which is bitter, slippery, caustic, and characteristically basic in reactions.

  2. Any of various soluble mineral salts found in natural water and arid soils.

  3. Alkali metal.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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alkali in Science
Plural alkalis or alkalies
A hydroxide of an alkali metal. The aqueous solution of alkalis is bitter, slippery, caustic, and characteristically basic in reactions.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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alkali in Culture
alkali [(al-kuh-leye)]

A bitter, caustic mineral often found in large beds in the desert. Alkalis are bases; two common examples are lye and ammonia.

Note: Plants have difficulty growing in soil that is rich in alkalis.
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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