Limewater is the common name for a diluted solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble in water (1.5 g/L at 25 °C). Pure limewater is clear and colourless, with a slight earthy smell and an alkaline bitter taste of calcium hydroxide. The term lime refers to the alkaline mineral, and is unrelated to the acidic fruit.
Limewater is used in the preparation of maize for corn tortillas and other culinary purposes using a process known as nixtamalization.