Condenser \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.

Source: Webster's Revised Unabridged Dictionary (1913)