Limewater is the common name for a dilute aqueous solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble at room temperature in water (1.5 g/L at 25 °C). "Pure" (i.e. less than or fully saturated) limewater is clear and colorless, with a slight earthy smell and an astringent/bitter taste.
an aqueous solution of slaked lime, used in medicine, antacids, and lotions, and to absorb carbon dioxide from the air. water containing naturally an unusual amount of calcium carbonate or calcium sulfate.