rein

(noun) one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse.

(noun) any means of control. Example: "He took up the reins of government."

(verb) control and direct with or as if by reins. Synonyms: harness, rein in, draw rein. Example: "Rein a horse."

(verb) stop or slow up one's horse or oneself by or as if by pulling the reins. Synonyms: rein in. Example: "They reined in in front of the post office."

(verb) stop or check by or as if by a pull at the reins. Synonyms: rein in. Example: "He reined in his horses in front of the post office."

(verb) keep in check. Synonyms: rule, harness. Example: "Rule one's temper."