outrunner

noun

1. An offshoot; a branch.

   “some out-runner of the river, where the streams run not strongly”

   “It is flanked on its east side by metamorphic Cretaceous limestone, which also forms the northern outrunner of this spur.”

2. A person or animal who accompanies a vehicle or procession but who is not seated in the vehicle or part of the procession.

   “Mail, guns and luggage aboard, and ourselves perched in the only seat of honor and comfort, that with the driver, we tore away through a long avenue lined with native shops, an outrunner hanging on for dear life to the more obstrepersous horse for the first quarter of a mile.”

   “It is supported by an outrunner trotting abreast, and retained by two as slender ropes, while a strap attaching his apology for a bridle to that of his neighbour hinders him from running at an angle of more than 45° to the line of progression.”

   “The outrunner of the Khedevial carriage comes along and the man on the box is silent, perhaps two outrunners speed ahead of the prancing horses clearing the way for the royal cortege.”

3. An electric motor having the rotor outside the stator.
4. One who outruns.

   “Such as in a game of backgammon one can be outrun, and other times one can be the outrunner, so are the brave-hearted riders, who roam the hunting ground sometimes apprehended, and other times become apprehenders themselves.”