Boiler meaning : A person who boils something. A steam boiler. An apparatus for heating circulating water or other heat transferring liquid. A device consisting of a heat source and a tank for storing hot water, typically for space heating, domestic hot water etc., disregarding the source of heat. A kitchen vessel for steaming, boiling or heating food. A sunken reef, especially a coral reef, on which the sea breaks heavily. A tough old chicken only suitable for cooking by boiling.