Pronunciation: (kup'lur), [key]
1. a person or thing that couples or links together.
2. Mach.a rod or link transmitting force and motion between a rotating part and a rotating or oscillating part.
3. Also called coupling. Railroads.a device for joining pieces of rolling stock.
4. a device in an organ or harpsichord for connecting keys, manuals, or a manual and pedals, so that they are played together when one is played.
5. Elect.a device for transferring electrical energy from one circuit to another, as a transformer that joins parts of a radio apparatus together by induction.
6. (in color photography) a chemical that reacts with the developer to produce one of the colors in a print or transparency.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.