What is "to reverse an engine"

Reverse \Re*verse"\, v. t. [imp. & p. p. Reversed (r[-e]*v[~e]rst");p. pr. & vb. n. Reversing.] [See Reverse, a., and cf. Revert.]

1. To turn back; to cause to face in a contrary direction; to cause to depart.

   And that old dame said many an idle verse, Out of her daughter's heart fond fancies to reverse.
   --Spenser.

2. To cause to return; to recall. [Obs.]

   And to his fresh remembrance did reverse The ugly view of his deformed crimes.
   --Spenser.

3. To change totally; to alter to the opposite.

   Reverse the doom of death.
   --Shak.

   She reversed the conduct of the celebrated vicar of Bray.
   --Sir W. Scott.

4. To turn upside down; to invert.

   A pyramid reversed may stand upon his point if balanced by admirable skill.
   --Sir W. Temple.

5. Hence, to overthrow; to subvert.

   These can divide, and these reverse, the state.
   --Pope.

   Custom . . . reverses even the distinctions of good and evil.
   --Rogers.

6. (Law) To overthrow by a contrary decision; to make void; to under or annual for error; as, to reverse a judgment, sentence, or decree.

   Reverse arms (Mil.), a position of a soldier in which the piece passes between the right elbow and the body at an angle of 45[deg], and is held as in the illustration.

   To reverse an engine or To reverse a machine, to cause it to perform its revolutions or action in the opposite direction.

   Syn: To overturn; overset; invert; overthrow; subvert; repeal; annul; revoke; undo.