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1. 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
    
2. Control and direct with or as if by reins
   "rein in a horse"
   - harness, draw rein, rein
    
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"
   - rein

Derived forms: reined in, reins in, reining in

Type of: command, control, halt, stop

Encyclopedia: Rein in