Of a formation of soldiers, to reverse the direction in which they are facing; an about face.
A complete change of opinion, direction, etc.
To turn to face the opposite direction.
The act of one who, or that which, backtracks; a retracing of one's steps.
The usage of a runway as a taxiway, especially at private strips and smaller airports.
The act of building all possible solutions to a problem incrementally, abandoning any candidate solution if it cannot lead to a valid solution.