cornerman

noun4

1. •
   A coach, trainer or other assistant who attends to a boxer between rounds.
2. •
   A player who can play both the small forward and power forward positions.
3. •
   (US, historical) A policeman assigned to an intersection to direct the traffic.

   • This cornerman is taking time out to provide directions to a driver. Their easily recognizable white hats and regular presence on their corners made these officers readily accessible […] — 2011
4. •
   Synonym of endman (“type of stock minstrel character”).