All 3 Uses

rein
in
Chandra's Wars
(Auto-generated)

He walks to the inside of the road, guiding them with his right hand, holding the reins to the side of the yoke.†
Chpt 2.10 *
Nelson tightens his grip on the reins and braces himself against the yoke.†
Chpt 2.10
When he sees me seeing him looking, he snaps his head back to the road and flicks the reins.†
Chpt 2.14

Definitions:

(1) (rein as in: to rein in their activities)
to restrain or control; or a means of control
The meaning of rein depends upon its context. For example:
- "keep a tight rein on the new employee," or "rein in a horse" -- to control or restrain
- "give the new employee free rein," or "give the horse full rein" -- do not restrain
- "the reins of government" -- means of control
- "the reins of the horse" -- leather straps used with a bit to control a horse (You might like to think of other senses of rein as being figurative derivations from this sense.)
(2) (meaning too rare to warrant focus)
to "give free rein" is not to restrain (not to exercise control over)