Definition of Alkaline in Chemstry

It's an aqueous solution with a pH greater than 7

Glass beakers or strong alkali level, and red for weak acidity level
Glass beakers indicating blue for weak alkaline level, green for strong alkali level, and red for weak acidity level. Trish Gant / Getty Images

Alkaline refers to an aqueous solution having a pH greater than 7 or a [OH-] greater than 10-7. An alkaline solution is also known as basic.