1.one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse
2.any means of control;
he took up the reins of government
1.control and direct with or as if by reins;
rein a horse
2.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
3.stop or check by or as if by a pull at the reins;
He reined in his horses in front of the post office
4.keep in check;
rule one's temper