Holdback /(?)/

Hold·back

Holdback

n.
  1. Check; hindrance; restraint; obstacle.
    The only holdback is the affection . . . that we bear to our wealth.
  2. The projection or loop on the thill of a vehicle. to which a strap of the harness is attached, to hold back a carriage when going down hill, or in backing; also, the strap or part of the harness so used.