reversal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act or an instance of reversing.
• noun The state of being reversed.
• noun A usually adverse change in fortune.
• noun Law The act or an instance of changing or setting aside a lower court's decision by a higher court.
• noun Sports A maneuver in wrestling in which a competitor being controlled by the opponent suddenly reverses the situation and gains control.

from The Century Dictionary.

• noun The act of reversing, or of altering a position, direction, action, condition, or state to its opposite or contrary; also, the state of being reversed.
• noun In physics, specifically, the changing of a bright line in a spectrum, produced by an incandescent vapor, into a dark line (by absorption), and the reverse.
• noun The act of repealing, revoking, or annulling; a change or overthrowing: as, the reversal of a judgment, which amounts to an official declaration that it is erroneous and rendered void or terminated; the reversal of an attainder or of an outlawry.
• noun In biology, reversion.
• Causing, intending, or implying reverse action; reversing.
• noun In international law: A promise by a sovereign power that a certain order, or certain conditions, promulgated or established, will be observed, notwithstanding changes that may occur to cause deviation therefrom. For instance, when France recognized Russia as an imperial government, a reversal was required that Russia would not cause any derogation from the rank which France had held toward her.
• noun A declaration by a sovereign that by a given act he means no prejudice to another power.
• noun In electricity, the process of changing the direction of the current in a circuit. In telegraphy the term is applied to the sending of signals over the line by means of rapidly reversed or alternating currents.

from the GNU version of the Collaborative International Dictionary of English.

• adjective obsolete Intended to reverse; implying reversal.
• noun The act of reversing; the causing to move or face in an opposite direction, or to stand or lie in an inverted position
• noun A change or overthrowing

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The state of being reversed.
• noun An instance of reversing.
• noun A change in fortune; a change from being successful to having problems.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an unfortunate happening that hinders or impedes; something that is thwarting or frustrating
• noun a judgment by a higher court that the judgment of a lower court was incorrect and should be set aside
• noun turning in the opposite direction
• noun a change from one state to the opposite state
• noun turning in an opposite direction or position
• noun a decision to reverse an earlier decision
• noun the act of reversing the order or place of
• noun a major change in attitude or principle or point of view