Coupling

Pronunciation: -l?ng
n.
  1. The act of bringing or coming together; connection; sexual union.
  2. (Mach.) A device or contrivance which serves to couple or connect adjacent parts or objects; as, a belt coupling, which connects the ends of a belt; a car coupling, which connects the cars in a train; a shaft coupling, which connects the ends of shafts.
    3. Box coupling, Chain coupling .
    See under Box, Chain.
    Coupling box ,
    a coupling shaped like a journal box, for clamping together the ends of two shafts, so that they may revolve together.
    Coupling pin ,
    a pin or bolt used in coupling or joining together railroad cars, etc.