Definition of alkali
plural alkalies
or alkalis
1
:a soluble salt obtained from the ashes of plants and consisting largely of potassium or sodium carbonate;
broadly
:a substance (such as a hydroxide or carbonate of an alkali metal) having marked basic properties — compare base 7a
2
:alkali metal
3
:a soluble salt or a mixture of soluble salts present in some soils of arid regions in quantity detrimental to agriculture
