check in
(to report your arrival at an airport, hotel, hospital, etc.)
- Passengers must check in at least an hour before the plane leaves.
- I’ll call the hotel and tell them that we’ll check in tomorrow.
check in American English informal
(to talk with someone in order to find out about something)
- I was just checking in to see what was going on.
- Listen to me; I have to check in with you about something.