rein in WordNet English dictionary

1. control and direct with or as if by reins
   "rein a horse"
   harness  rein in  draw rein  rein 
   
2. keep in check
   "rule one's temper"
   rule  harness  rein 
   
3. 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"
   rein  rein in 
   
4. stop or check by or as if by a pull at the reins
   "He reined in his horses in front of the post office"
   rein  rein in 
   

1. one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse
   rein 
   
2. any means of control
   "he took up the reins of government"
   rein