from
The Collaborative International Dictionary of English v.0.48
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.
[1913 Webster]
He mounts and reins his horse. --Chapman.
[1913 Webster]
2. To restrain; to control; to check.
[1913 Webster]
Being once chafed, he can not
Be reined again to temperance. --Shak.
[1913 Webster]
{To rein in} or {To rein up},
(a) to check the speed of, or cause to stop, by drawing
the reins. Hence,
(a) to cause (a person) to slow down or cease some
activity; -- to rein in is used commonly of superiors
in a chain of command, ordering a subordinate to
moderate or cease some activity deemed excessive.
[1913 Webster +PJC]