limescale

lime scale |ˈlīmˌskāl ˈlaɪmskeɪl | ▶noun chiefly Brit. a whitish deposit on the inside of pipes, pots, and kettles, caused by minerals leeched from the water.

limescale

lime |scale |ˈlʌɪmskeɪl | ▶noun [ mass noun ] Brit. a hard white substance consisting chiefly of calcium carbonate, deposited by water on the inside of pipes, kettles, etc.