saddle-sore (Adjective) — (of a rider) sore after riding a horse.
saddle-sore (Noun) — An open sore on the back of a horse caused by ill-fitting or badly adjusted saddle.
saddle-sore (Noun) — Sore on a horseback rider chafed by a saddle. ex. "If you get a saddle sore, keep pressure off it and apply a drawing salve"