Military . a turn of 180? from the position of attention.

a complete, sudden change in position, direction, principle, attitude, etc.

They've done an about-face in their foreign policy.

to execute an about face.

to turn in the opposite direction.

to switch to an opposite opinion.

noun

180 degree turn , change , change in direction , changeabout , double , doubleback , overturning , policy change , repeal , retraction , reversal , reverse , switch , turn , turnabout , turnaround , u-turn , volte-face , flip-flop

verb

reverse