back strap (bakstrap)

A broad strap pa ing along the middle of a horse's back from the upper hame-strap to the crupper or a point of junction with the hip-straps in a wagon-har ne , and in a carriage-harne from the gigback-strapped (bak's trapt), p. a. Carried by head-winds to the back of a cape or promontory: saddle to the crupper. H. Knight. said of a ship. an up-stream.