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1. Turn, usually 180 degrees
    
2. Change one's mind and assume the opposite viewpoint

1. Act of pivoting 180 degrees, especially in a military formation
   - about turn
    
2. A major change in attitude, principle or point of view
   "an about-face on foreign policy";
   - volte-face, reversal, policy change

Derived forms: about-facing, about-faces, about-faced

Type of: change, rethink, reversal, reverse, reversion, turn, turnabout [N. Amer], turnaround

Encyclopedia: About-face