- The definition of an alkali is a soluble salt that comes from the ashes of plants and is made up of mostly potassium or sodium carbonate.
Lye and calcium carbonate are each an example of an alkali.
nounpl. alkalies or alkalis
- any base or hydroxide, as soda, potash, etc. that is soluble in water and gives a high concentration of hydroxyl ions in solution; specif., any of the hydroxides and carbonates of the alkali metals
- any soluble substance, as a mineral salt or mixture of salts, that can neutralize acids, has a pH greater than 7.0, and turns litmus blue: strong alkalies are caustic
Origin of alkaliMiddle English alkaly ; from Arabic al-qily, for al-qili, the ashes (of saltwort) ; from qalai, to roast in a pan
nounpl. al·ka·lis or al·ka·lies
- A carbonate or hydroxide of an alkali metal, the aqueous solution of which is bitter, slippery, caustic, and characteristically basic in reactions.
- Any of various soluble mineral salts found in natural water and arid soils.
- Alkali metal.
- A substance having highly basic properties; a strong base.
Origin of alkaliMiddle English, alkaline substance from calcined plant ashes, from Medieval Latin, from Arabic al-qily, the ashes, lye, potash : al-, the + qily, ashes (from qalā, to fry, roast; see qly in Semitic roots).
(plural alkalies or alkalis)
- (chemistry) One of a class of caustic bases, such as soda, potash, ammonia, and lithia, whose distinguishing peculiarities are solubility in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue.
- Soda ash; caustic soda, caustic potash, etc.
- (Western United States) Soluble mineral matter, other than common salt, contained in soils of natural waters.
French alcali, ultimately from Arabic القلي (al-qilī, “ashes of the saltwort”), from قلى (qalā, “to roast in a pan, fry”).