1. 碱
An alkali is a substance with a pH value of more than
7. Alkalis form chemical salts when they are combined with acids.

1. any of various water-soluble compounds capable of turning litmus blue and reacting with an acid to form a salt and water

e.g. bases include oxides and hydroxides of metals and ammonia

Synonym: base

2. a mixture of soluble salts found in arid soils and some bodies of water
detrimental to agriculture