Surveying . the interval by which a chain or tape exceeds the length being measured.

setback ( def. 4 ) .

noun

achievement , advance , blessing , boon , boost , success

noun

about-face * , backset , bath * , blow , bottom , check , comedown , defeat , delay , difficulty , drawing board , flip-flop * , hindrance , hitch * , hold-up , impediment , misfortune , obstacle , rebuff , regress , regression , reversal , reversal of fortune , reverse , slowdown , stumbling block * , trouble , upset , whole new ballgame , (colloq.) backset , disappointment , loss , relapse , repulse