Someone who is grounded makes good decisions and does not say or do stupid things.

He's very grounded even though he has so much money. 虽然他这么有钱，但他的头脑还是很清醒。

used to describe an aircraft that is prevented from flying for some reason, or a ship that cannot move because it has hit solid ground

A child or young person who is grounded is not allowed to go out as a punishment.

I stayed out til 1 am last night and now I'm grounded for a week. 昨天晚上我凌晨一点才回家，现在被罚一个星期不许出门。