Con*dens"er (?), n. 1. One who, or that which, condenses.

2. (Physic) (a) An instrument for condensing air or other elastic fluids, consisting of a cylinder having a movable piston to force the air into a receiver, and a valve to prevent its escape. (b) An instrument for concentrating electricity by the effect of induction between conducting plates separated by a nonconducting plate. (c) A lens or mirror, usually of short focal distance, used to concentrate light upon an object.

3. (Chem.) An apparatus for receiving and condensing the volatile products of distillation to a liquid or solid form, by cooling.

4. (Steam Engine) An apparatus, separate from the cylinder, in which the exhaust steam is condensed by the action of cold water or air. See Illust. of Steam engine.

Achromatic condenser(Optics), an achromatic lens used as a condenser. -- Bull's-eye condenser, or Bull's-eye(Optics), a lens of short focal distance used for concentrating rays of light. -- Injection condenser, a vessel in which steam is condensed by the direct contact of water. -- Surface condenser, an apparatus for condensing steam, especially the exhaust of a steam engine, by bringing it into contact with metallic surface cooled by water or air.