What is Alkali?

Legal Definition
In chemistry, an alkali (/ˈælkəl/; from Arabic: al-qaly القلي, القالي , “ashes of the saltwort”) is a basic, ionic salt of an alkali metal or alkaline earth metal chemical element. An alkali also can be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The adjective alkaline is commonly, and alkalescent less often, used in English as a synonym for basic, especially for bases soluble in water. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base, and they are still among the most common bases.
-- Wikipedia
Legal Definition
A water soluable base that feels soapy. It has a ph level of above 7 and makes the litmust papers turn blue on contact. Burns result from exposure to strong alkalis.