set back I. transitive verb 1.: hinder, check, delay < the harvest was set back by bad weather > 2.: to cause (a timepiece) to indicate an earlier time < forgot to set his watch back on his trip west > 3.: to defeat (an opponent) with the effect that points are subtracted from the opposing score (as in a card game) II. transitive verb : cost < how much a diamond would set you back > III. noun : an offensive back in football who usually lines up behind the quarterback