The term condenser has the following meanings:

• In electronics, it is another (more old-fashioned) word for capacitor.
• In electrical engineering, a synchronous condenser is a rotating machine similar to a motor, used to control reactive power flow on an electric power transmission system.
• In systems involving heat transfer, a condenser is a heat exchanger which converts a substance from its gaseous to its liquid state. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant. For example a refrigerator uses a condenser to get rid of the heat extracted from the interior of the unit to the outside air. Condensers are widely used in many types of system.
• In optics, a condenser is a large plano-convex lens, commonly used in pairs in the illumination system present in projectors, microscopes, and photographic enlargers
• A condenser microphone uses a capacitive diaphragm element to convert sound to electrical signals.
• In chemistry, a condenser is the apparatus in which some type of condensation occurs.