What is the meaning 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.
  • usage: "he took up the reins of government"

verb

• Control and direct with or as if by reins.
  • usage: "rein a horse"
  • synonyms: harness, rein in, draw rein
• Stop or slow up one's horse or oneself by or as if by pulling the reins.
  • usage: "They reined in in front of the post office"
  • synonyms: rein in
• Stop or check by or as if by a pull at the reins.
  • usage: "He reined in his horses in front of the post office"
  • synonyms: rein in
• Keep in check.
  • usage: "rule one's temper"
  • synonyms: rule, harness