Meaning of rein
Definition of rein
(noun)
one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse
any means of control; "he took up the reins of government"
stop or slow up one's horse or oneself by or as if by pulling the reins; "They reined in in front of the post office"
stop or check by or as if by a pull at the reins; "He reined in his horses in front of the post office"
keep in check; "rule one's temper"