formal a sudden change of a belief or plan to the opposite of what it was before.
In the early 90's he made a complete political volte-face, moving from the Republican Party to the Democrats.
volte-face
A complete change of opinion or belief. The phrase comes from the Italian term voltafaccia. Everyone was surprised when the candidate made a complete volte-face on her stance on taxes.
a volte-ˈface
(from French, formal) a complete change of opinion or plan: This represents a volte-face in government policy.This is a French adaptation of an Italian phrase and refers to turning to face the opposite direction.