volte-face

volte-face \vawlt-FAHS; vawl-tuh-\, noun:

An about-face; a reversal, as in policy or opinion.

I was eventually eased out of the organisation, but not before British policy had performed a volte-face on Cyprus, the colony had gained independence, and yesterday's political wisdoms had suddenly been repudiated.
-- George Urban, Radio Free Europe and the Pursuit of Democracy

In a sudden volte-face, he seemed to accept the agreement; then, when the besieged forces came out to embark, he had their barges held in port.
-- Richard Eder, "Just Wild About Horatio", New York Times, November 7, 1999

Suddenly confronted with the imminent ruin of Angela Lyne, his former mistress, who is drinking herself to death out of loneliness, he does the first real volte-face of his life by returning to her.
-- L.E. Sissman, "Evelyn Waugh: The Height of His Powers", The Atlantic, March 1972

Volte-face comes from French, from Italian voltafaccia, from volta, "turn" + faccia, "face."