Definition of coupler
something that connects two things, especially mechanical components or systems:a hydraulic coupler [as modifier]:coupler rod Music a device in an organ for connecting two manuals, or a manual with pedals, so that they both sound when only one is played. Music (also octave coupler) a device in an organ for connecting notes with their octaves above or below. Photography a compound in a developer or an emulsion that combines with the products of development to form an insoluble dye, part of the image. (also acoustic coupler) a modem that converts digital signals from a computer into audible sound signals and vice versa, so that the former can be transmitted and received over telephone lines.