Alkali (noun)

1. A substance that neutralizes acids and forms salts, typically a metal hydroxide or a soluble base.
2. A substance that has a pH greater than 7.

Origin:

Late 18th century: from arabic al-qaly "the ashes", from the ashes of saltwort plants used to make soda ash.

Examples:

1. The solution was found to contain a high concentration of alkali.
2. An alkali metal such as sodium or potassium.
3. Alkali soils, which are typically found in dry regions.
4. The alkali was added to neutralize the acid.
5. The alkali test is used to determine the amount of alkali in a substance.