Other forms: couplings
A coupling is the link that joins one vehicle to the next. A broken coupling, automatic coupling, check the coupling.
Railways moved from a chain and a hook, which had to be linked by a man standing between the wagons and killed many, to automatic couplings that lock when the wagons touch. In engineering generally a coupling joins two rotating shafts.
1nouncouplingThe link that joins one vehicle to the next.
“The coupling between the last two carriages broke, and they rolled away down the hill.”
coupling is a link.
Couple plus -ing, from Latin copula, a bond or tie.
Middle English
couplynge
English, today
coupling
From Middle English couplynge; equivalent to couple + -ing.
Etymology from Wiktionary, CC BY-SA