one who, or that which, condenses.-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.-an instrument for concentrating electricity by the effect of induction between conducting plates separated by a nonconducting plate.-a lens or mirror, usually of short focal distance, used to concentrate light upon an object.-an apparatus for receiving and condensing the volatile products of distillation to a liquid or solid form, by cooling.-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.