noun (plural alkalis)
- a chemical compound that neutralizes or effervesces with acids and turns litmus blue; typically, a caustic or corrosive substance of this kind such as lime or soda. Often contrasted with acid; compare with base1.
Alkalis release hydroxide ions (OH) when dissolved in water. An alkaline solution has a pH greater than 7
late Middle English (denoting a saline substance derived from the ashes of various plants, including glasswort): from medieval Latin, from Arabic al-ḳalī 'calcined ashes (of the glasswort, etc.)', from ḳalā 'fry, roast'