The Free On-line Dictionary of Computing (30 December 2018):

wormhole routing

    A property of a message passing system in which
   each part of a message is transmitted independently and one
   part can be forwarded to the next node before the whole
   message has been received.  All parts of a single message
   follow the same route.

   The independent parts are normally small, e.g. one 32-bit
   word.  This reduces the latency and the storage requirements
   on each node when compared with message switching where a
   node receives the whole message before it starts to forward it
   to the next node.  It is more complex than message switching
   because each node must keep track of the messages currently
   flowing through it.

   With cut-through switching, wormhole routing is applied to
   packets in a packet switching system so that forwarding of
   a packet starts as soon as its destination is known, before
   the whole packet had arrived.

   (2003-05-15)