(0. Eng. steam, vapour, smoke, cf. Du. stoom; the origin is unknown), water-vapour. Dry steam is steam free from mechanically mixed water particles; wet steam, on the other hand, contains water particles in suspension. Saturated steam is steam in contact with liquid water at a temperature which is the boiling point of the water and condensing point of the steam; superheated steam is steam out of contact with water heated above this temperature. For theoretical considerations see Vaporization, and for the most important application see Steam Engine; also Water.