To set upon in the rear.To plow again, in the autumn, prairie-land which has been plowed for the first time in the preceding spring.n. A setting back or backward, as the result of some untoward circumstance or opposing agency; a check to progress; retardation, or the losing of ground; a relapse: as, he suffered more than one serious backset; a backset which appeared to be fatal.n. An eddy or counter-current in flowing water.n. In lock-making, the horizontal distance between the front of the lock and the center of the keyhole: an essential measurement in lock-fitting.