about-face (
http://definr.com/about-face)
n 1: act of pivoting 180 degrees, especially in a military
formation [syn:
about turn]
2: a reversal in attitude or principle or point of view: "an
about-face on foreign policy" [syn:
volte-face,
reversal,
policy change]
v 1: turn, usually 180 degrees
2: change one's mind and assume the opposite viewpoint