alkali

American  

[al-kuh-lahy] / ˈæl kəˌlaɪ /

noun

alkalis, plural alkalies plural

1. Chemistry.

   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.

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.

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adjective

1. Chemistry. alkaline.

alkali British  

/ ˈælkəˌlaɪ /

noun

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

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alkali Scientific  

/ ăl′kə-lī′ /

alkalis plural

1. A hydroxide of an alkali metal. The aqueous solution of alkalis is bitter, slippery, caustic, and characteristically basic in reactions.

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alkali Cultural  

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

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Discover More

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

Etymology

Origin of alkali

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

Example Sentences

These bacteria produce acid but are weak at generating alkali.

From Science Daily • Jan. 9, 2026

Lynn Boulton, the Sierra Club’s local conservation chair, walked along a dirt road to what was once a marshy alkali meadow.

From Los Angeles Times • Oct. 18, 2025

The low-carbon seawater then has alkali added to it – to neutralise the acid that was added – and is then pumped back out into a stream that flows into the sea.

From BBC • Apr. 17, 2025

Another Los Angeles Times report on a roundup of immigrants begins by noting, “Human misery was compounded here today by a blistering desert sun and swirls of alkali dust.”

From Salon • Sep. 21, 2024

He drifted past saguaros and alkali flats, camped beneath escarpments of naked Precambrian stone.

From "Into the Wild" by Jon Krakauer