rêne « She gripped the reins tightly. »
to give sb free rein = donner carte blanche à qn « The government gave free rein to the private sector in transport. »
to keep a tight rein on sth = exercer un contrôle strict sur qch « The Government is keeping a tight rein on public expenditure. »
to rein in = réfréner « He has had to rein in his enthusiasm. »« The government finally reined in inflation by sending interest rates soaring. »