Backset

Back"set` (-sĕt`), n. [Back, adv. + set.] 1. A check; a relapse; a discouragement; a setback.

2. Whatever is thrown back in its course, as water.

Slackwater, or the backset caused by the overflow.
Harper's Mag.

Back"set`, v. t. To plow again, in the fall; -- said of prairie land broken up in the spring. [Western U.S.]