Source : Webster's Revised Unabridged Dictionary (1913)

Rein \Rein\, v. t. [imp. & p. p. {Reined} (r?nd); p. pr. & vb.
   n. {Reining}.]
   1. To govern or direct with the reins; as, to rein a horse
      one way or another.

            He mounts and reins his horse.        --Chapman.

   2. To restrain; to control; to check.

            Being once chafed, he can not Be reined again to
            temperance.                           --Shak.

   {To rein in} or {rein up}, to check the speed of, or cause to
      stop, by drawing the reins.