coupler

noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about coupler at Wordnik → Where our words come from →

1. Someone who couples things together, especially someone whose job it is to couple railway carriages.
2. Anything that serves to couple things together; but especially a device that couples railway carriages.
3. A device that connects two keyboards of an organ together so that they play together.