ˈalkəˌlī noun
( plural alkalies or alkalis -īz)
Usage: often attributive
Etymology: Middle English, from Medieval Latin alcali, alkali, from Arabic al-qili the ashes of the plant saltwort
1.
a. : a soluble salt obtained from the ashes of plants and consisting largely of potassium carbonate or (as from sea plants) of sodium carbonate
b. : a substance having marked basic properties like the above salts ; especially : a hydroxide or carbonate of an alkali metal (as sodium or potassium) or less often of an alkaline-earth metal (as calcium) — see caustic alkali ; compare base 8
2. : alkali metal — used especially in names of compounds
alkali cyanides
3.
a. : a soluble salt or a mixture of soluble salts (as the sulfates and chlorides of sodium, potassium, and magnesium and the carbonates of sodium and potassium) present in some soils of arid or semiarid regions in quantity detrimental to ordinary agriculture
alkali soils
b. : a region in which the soil abounds in alkali