octave coupler

noun

1. a mechanism on an organ and on some harpsichords that enables keys or pedals an octave apart to be played simultaneously

Example Sentences

Shortly after the introduction of pneumatic action, an organ with an occasional octave coupler, that is a coupler which depressed a key an octave higher or lower than the one originally struck, was sometimes met with.

From Project Gutenberg

The octave coupler stop, sometimes called Harmonique, controls an arrangement whereby, when a key is depressed, its octave is made to sound also.

From Project Gutenberg