Learn how to say Coupler correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word coupler:
a link or rod transmitting power between two rotating mechanisms or a rotating part and a reciprocating part
(music) a device on an organ or harpsichord connecting two keys, two manuals, etc, so that both may be played at once
(electronics) a device, such as a transformer, used to couple two or more electrical circuits
(US & Canadian) a device for connecting railway cars or trucks together Also called (in eg Britain): coupling