Hvad er steam? Hvad er steam? The vapor phase of water.A mist of cooling water vapor.Pressurized water vapor used for heating, cooking, or to provide mechanical power. The power produced by a machine using pressurized water vapor.Steam heating.Power; energy.To produce or emit steam.To become or rise up as steam.To become misted or covered with steam.To move by means of steam power.Informal To become very angry; fume.To expose to steam, as in cooking.