n.
Function: transitive verb
Date: 15th century
1 : to control or direct with or as if with reins
2 : to check or stop by or as if by a pull at the reins < rein ed in her horse> <couldn't rein his impatience>
intransitive verb
1 archaic : to submit to the use of reins
2 : to stop or slow up one's horse or oneself by or as if by pulling the reins