rein

n. [ F. rêne, fr. (assumed) LL. retina, fr. L. retinere to hold back. See Retain. ] 1. The strap of a bridle, fastened to the curb or snaffle on each side, by which the rider or driver governs the horse. [ 1913 Webster ]

This knight laid hold upon his reyne. Chaucer. [ 1913 Webster ]

2. Hence, an instrument or means of curbing, restraining, or governing; government; restraint. “Let their eyes rove without rein.” Milton. [ 1913 Webster ]

To give rein,
To give the rein to, to give license to; to leave withouut restrain. --
To take the reins, to take the guidance or government; to assume control. [ 1913 Webster ]

v. t. [ imp. & p. p. Reined 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 ]

v. t. To inaugurate anew. [ 1913 Webster ]

v. t. To incite again. [ 1913 Webster ]

v. t. To incorporate again. [ 1913 Webster ]

v. t. To increase again. [ 1913 Webster ]

v. t. To incur again. [ 1913 Webster ]

n. [ Icel. hreinn reindeer + E. deer. Icel. hreinn is of Lapp or Finnish origin; cf. Lappish reino pasturage. ] [ Formerly written also raindeer, and ranedeer. ] (Zool.) Any ruminant of the genus Rangifer, of the Deer family, found in the colder parts of both the Eastern and Western hemispheres, and having long irregularly branched antlers, with the brow tines palmate. [ 1913 Webster ]

☞ The common European species (Rangifer tarandus) is domesticated in Lapland. The woodland reindeer or caribou (Rangifer caribou) is found in Canada and Maine (see Caribou.) The Barren Ground reindeer or caribou (Rangifer Groenlandicus), of smaller size, is found on the shores of the Arctic Ocean, in both hemispheries. [ 1913 Webster ]

Reindeer moss (Bot.), a gray branching lichen (Cladonia rangiferina) which forms extensive patches on the ground in arctic and even in north temperature regions. It is the principal food of the Lapland reindeer in winter. --
Reindeer period (Geol.), a name sometimes given to a part of the Paleolithic era when the reindeer was common over Central Europe. [ 1913 Webster ]