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"
   

2. control and direct with or as if by reins;

   "rein a horse"
   

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"
   

1.控制;约束
Torein in something means to control it.

e.g. His administration's economic policy would focus on reiningin inflation...
他的政府的经济政策将侧重于控制通货膨胀。
e.g. Mary spoiled both her children, then tried too late torein themin.
玛丽惯坏了她的两个孩子，想要管束他们的时候已经来不及了。

2.拉紧(马的)缰绳;勒缰（使马停步）
If yourein in a horse, you stop it or cause it to go more slowly by pulling its reins.

e.g. The horsemen reinedin and shouted at the men behind to turn back...
骑手们勒缰停住，对身后的人大嚷，让他们回去。
e.g. Mrs Glick reinedin the horse and stopped at the crossroads.
格利克夫人勒住缰绳在十字路口停了下来。

1. 放慢：reinin a horse 勒住马 |reinin 放慢 |rein up a horse 猛然勒马

2. 严格控制,严加管束：reckon with 1.估计到,预料到2.处理,对付 |reinin 严格控制,严加管束 | revolve around 以......为主要内容

3. 放慢,控制：registered capital 注册资本 notice: registered |reinin 放慢,控制 | primary school 小学