Source : Webster's Revised Unabridged Dictionary (1913)

Reversal \Re*ver"sal\, n. [From {Reverse}.]
   1. The act of reversing; the causing to move or face in an
      opposite direction, or to stand or lie in an inverted
      position; as, the reversal of a rotating wheel; the
      reversal of objects by a convex lens.

   2. A change or overthrowing; as, the reversal of a judgment,
      which amounts to an official declaration that it is false;
      the reversal of an attainder, or of an outlawry, by which
      the sentence is rendered void. --Blackstone.

Reversal \Re*ver"sal\, a. [See {Reverse}.]
   Intended to reverse; implying reversal. [Obs.] --Bp. Burnet.

Source : WordNet®

reversal
     n 1: a change from one state to the opposite state; "there was a
          reversal of autonomic function"
     2: an unfortunate happening that hinders of impedes; something
        that is thwarting or frustrating [syn: {reverse}, {setback},
         {blow}, {black eye}]
     3: turning in an opposite direction or position; "the reversal
        of the image in the lens" [syn: {turn around}]
     4: a decision to reverse an earlier decision [syn: {change of
        mind}, {flip-flop}, {turnabout}, {turnaround}]
     5: a judgment by a higher court that the judgment of a lower
        court was incorrect and should be set aside [ant: {affirmation}]
     6: turning in the opposite direction [syn: {reversion}, {reverse},
         {turnabout}, {turnaround}]
     7: the act of reversing the order or place of [syn: {transposition}]
     8: a reversal in attitude or principle or point of view; "an
        about-face on foreign policy" [syn: {about-face}, {volte-face},
         {policy change}]