rein rein /ˈreɪn/

noun

1. () One of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse  ( rein )
   one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse
    The rider held onto the reins tightly as she directed the horse through the course
   The rider held onto the reins tightly as she directed the horse through the course
   
   
2. Any means of control  ( rein )
   any means of control
    He took up the reins of government
   he took up the reins of government
   

verb

1. () Control and direct with or as if by reins  ( harness , rein in , draw rein , rein )
   control and direct with or as if by reins
    Rein a horse
   rein a horse
   
2. Keep in check  ( harness , rein , rule )
   keep in check
    Rule one's temper
   rule one's temper
   
3. Stop or check by or as if by a pull at the reins  ( rein , rein in )
   stop or check by or as if by a pull at the reins
    He reined in his horses in front of the post office
   He reined in his horses in front of the post office
   
4. (driving) stop or slow up one's horse or oneself by or as if by pulling the reins  ( rein , rein in )
   (driving) 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
   They reined in in front of the post office