【俚语】

1.（在旅馆）登记入住;(在门诊部)挂号

【例句】

When you check in or check into a hotel or clinic, or if someone checks you in, you arrive and go through the necessary procedures before you stay there.
I'll ring the hotel. I'll tell them we'll check in tomorrow...

我来给旅馆打电话，通知他们我们明天入住。

2.(在机场)办理登机手续，检票登机