al|ka|li

al|ka|li «AL kuh ly», noun, plural -lis or -lies, adjective.

–n.

1. any one of a group of bitter-tasting substances that neutralizes acids and forms salts with them, and turns red litmus paper blue. Alkalis are soluble in water and often produce caustic solutions. Lye and ammonia are two common alkalis. In its most restricted, but most usual, sense alkali is applied only to the hydrates of lithium, sodium, potassium, rubidium, cesium, francium, and ammonium. In a more general sense it is applied to the hydrates of the alkaline-earth metals, and also to the alkaloids.

2. the soluble part of the ashes of marine plants, chiefly the carbonates of sodium or potassium; soda ash.

3. any salt or mixture of salts that neutralizes acids. Some desert soils contain much alkali, which is usually harmful to crops.

4. Western U.S. a region abounding in alkali: »

Sunrise found the white stage lurching eternally on across the alkali (Owen Wister).

–adj.

alkaline: »

an alkali base.

╂[< Middle French alcali < Arabic al-qalī the ashes of saltwort]