<p><strong>Noun</strong></p><ul><li>a person or thing that couples or links together.</li><li>a rod or link transmitting force and motion between a rotating part and a rotating or oscillating part.</li><li>also called coupling.</li><li>a device for joining pieces of rolling stock in railroads.</li><li>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.</li><li>a device for transferring electrical energy from one circuit to another, as a transformer that joins parts of a radio apparatus together by induction.</li><li>in color photography, a chemical that reacts with the developer to produce one of the colors in a print or transparency.</li></ul>