volte-face
From Longman Dictionary of Contemporary Englishvolte-facevolte-face /ˌvɒlt ˈfæsˌ -ˈfɑːs $ ˌvɒːlt ˈfɑːs/ noun [countable usually singular] CHANGE FROM ONE THING TO ANOTHER formal a change to a completely opposite opinion or plan of action SYN U-turnExamples from the Corpusvolte-face• By the end of the year, though, he appeared to have performed a volte-face.• One is the difficulty of explaining Hastings' apparent volte-face.• This explains the miraculous volte-face that took place in 1868.