alkali
Americannoun
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Chemistry.
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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.
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any of various other more or less active bases, as calcium hydroxide.
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(not in technical use) an alkali metal.
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Obsolete. any of various other compounds, as the carbonates of sodium and potassium.
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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.
adjective
noun
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chem a soluble base or a solution of a base
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a soluble mineral salt that occurs in arid soils and some natural waters
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Plants have difficulty growing in soil that is rich in alkalis.
Other Word Forms
Noun Inflected Forms
Etymology
Origin of alkali
1300–50; Middle English alkaly < Middle French alcali < dialectal Arabic al-qalī, variant of Arabic qily saltwort ashes
Vocabulary lists containing alkali
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.
See Examples For:
And he has seen them descend on Mono Lake when the water is teeming with brine shrimp and the larvae and pupae of alkali flies.
From Los Angeles Times ● Aug. 22, 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
Using the proposed method, larger alkali metal ions such as cesium could be incorporated into the perovskite structure, leading to ferroelectrics with desirable dielectric properties.
From Science Daily ● Apr. 25, 2024
A man suspected of an alkali attack in south London should not have been granted asylum, according to Home Office guidelines.
From BBC ● Feb. 2, 2024
Experiments of the German Gerhard Schramm, first published in 1944, reported that TMV particles in mild alkali fell apart into free RNA and a large number of similar, if not identical, protein molecules.
From "Double Helix" by James D. Watson
Pots, pans, vats, machines exposed to corrosives will be protected by a skin of aluminum, metal highly resistant to mos.t acids and alkalies.
From Time Magazine Archive
I understand that, in modern chemistry, the acids and alkalies are the two extremes of a class of substances called hydrates, the only difference being the radical.
They make it clear that there has been an introduction of fluorine and boron and a diminution in the alkalies during the transformation of the granitic rock into the greisen.
From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 5 "Greek Law" to "Ground-Squirrel" by Various
Lime, and the alkalies, are generally safe and useful additions, in connection with clover as a green manure; these may be applied to almost any worn soils with great advantage.
From American Pomology Apples by Warder, J. A.
It is saponified by alkalies, with reproduction of soluble gum.
From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 6 "Groups, Theory of" to "Gwyniad" by Various
In addition, the scientists substituted ammonium and tetramethyl ammonium, the former of which is mildly acidic, for the alkalis.
From Science Daily ● Feb. 12, 2024
Fermenting encompasses a range of processes through which microorganisms — yeasts, molds, bacteria — break down compounds in food to create alcohols, acids or alkalis, which in turn prevent the growth of harmful pathogens.
From Salon ● Dec. 6, 2023
Coal provided the power; the nascent chemical industry supplied the acids and alkalis essential to these enterprises.
From Nature ● Aug. 30, 2020
Alkalis were extracted from ashes, and soaps were prepared by combining these alkalis with fats.
From Textbooks ● Feb. 14, 2019
But the earths resembled alkalis, inasmuch as they too combined with, and so neutralized, acids.
From Heroes of Science Chemists by Muir, M. M. Pattison (Matthew Moncrieff Pattison)
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.
