English▸ noun (chiefly in military contexts) a turn made so as to face the opposite direction:
he did an about-face and marched out of the tent.
▪ a complete change of opinion or policy:
he threatened to stop helping us, but did a complete about-face.
▸ verb [no object] turn so as to face the opposite direction:
suddenly he about-turned and saluted again.
▸ exclamation (about face!) (in military contexts) a command to make an about-face.
– ORIGIN late 19th century (originally as a military command): shortening of right about turn.