[ al-kuh-lahy ]
See synonyms for alkali on
noun,plural al·ka·lis, al·ka·lies.
  1. Chemistry.

    • 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.

    • any of various other more or less active bases, as calcium hydroxide.

    • (not in technical use) an alkali metal.

    • Obsolete. any of various other compounds, as the carbonates of sodium and potassium.

  2. 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.

  1. Chemistry. alkaline.

Origin of alkali

1300–50; Middle English alkaly<Middle French alcali<dialectal Arabic al-qalī, variant of Arabic qily saltwort ashes

Words Nearby alkali Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use alkali in a sentence

British Dictionary definitions for alkali


/ (ˈælkəˌlaɪ) /

nounplural -lis or -lies
  1. chem a soluble base or a solution of a base

  2. a soluble mineral salt that occurs in arid soils and some natural waters

Origin of alkali

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 Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for alkali


[ ălkə-lī′ ]

Plural alkalis alkalies
  1. 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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for 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.

Notes for alkali

Plants have difficulty growing in soil that is rich in alkalis.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.