coupler

• POS: Noun
• HYPHEN: cou=pler

CIDE DICTIONARY

coupler, n. 

 One who couples; that which couples, as a link, ring, or shackle, to connect cars.  [1913 Webster]

Coupler of an organ, a contrivance by which any two or more of the ranks of keys, or keys and pedals, are connected so as to act together when the organ is played.

OXFORD DICTIONARY

coupler, n.
1 Mus. a a device in an organ for connecting two manuals, or a manual with pedals, so that they both sound when only one is played. b (also octave coupler) a similar device for connecting notes with their octaves above or below.
2 anything that connects two things, esp. a transformer used for connecting electric circuits.