check in/check into sth
phrasal verb with check verb uk/tʃek/ us
TRANSPORT
to go to a desk at an airport, port, etc., or a hotel and say that you have arrived:
Passengers are requested to check in two hours before the flight.
Please check in at the reception desk when you arrive.
It was late when we arrived in New York so we checked into a hotel near the airport.
INTERNET, TRANSPORT
to use the internet to check in for a flight:
You will find it most convenient to check in online.