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