From Longman Dictionary of Contemporary Englishcheck in phrasal verb1 TTAif you check in or are checked in at a hotel or airport, you go to the desk and report that you have arrived Check in two hours before the flight. at He checked in at the Europa Hotel.check somebody ↔ in Airline employees were checking in passengers. → check-in2 check something ↔ in to leave your bags at an official place so they can be put on a plane or a train, or to take someone’s bags in order to do this I said goodbye and went to check in my suitcases.3 American English to call someone to tell them that you are safe or where you are He just called to check in and tell them how he was doing.4 if a user of a social networking system checks in to a place, they show on the system that they are there → check→ See Verb table
Examples from the Corpus
check at• They had checked in at 1: 30 in the morning on a Saturday.• But with electronic ticketing, you can still get advanced seat assignments, check in at curbside and accrue frequent flier mileage.• The bill checks in at just under $ 12, and the meal serves two easily.• Transfer to Kaprun and check in at the hotel.• And once you're online your mail program can automatically check in at whatever interval you like.check-inˈcheck-in noun 1 [singular]TTA a place where you report your arrival at an airport, hotel, hospital etc the check-in desk Make sure you’re at the check-in by 5.30.2 [uncountable]TTA the process of reporting your arrival at an airport, hotel, hospital etc Ask your travel agent about check-in times.3 [countable] the act of showing on a social networking system that you are at a particular place → check in at check1Examples from the Corpus
check-in• In addition, the automated check-in facility will alert readers to current issues of periodicals as soon as they are processed.• Some have eliminated curb-side baggage check-in, which have caused some airport delays.• The hotel is hiring additional staff to make check-in easier.• On the ground, you enjoy separate check-in and a private lounge.• Separate check-in at London Gatwick. 20 kilos baggage allowance.• Swissair offers a telephone check-in facility for first and business class passengers with hand baggage.check-in desk• The main door went into a small lobby with a check-in desk.• It's more like the check-in desk at Motel 6.• The passenger must pass through a security gate before reaching the check-in desk.• When we get to the check-in desk the kids are already heading toward the swim-ming pool which is lit up bright blue.From Longman Business Dictionarycheck something ↔ in phrasal verb [intransitive, transitive]TRAVEL to go to the desk at a hotel or airport and say that you have arrivedThe keycard is authorised automatically when the guest checks in.His suitcase was already checked in. → check→ See Verb tablecheck-inˈcheck-in noun [singular]TRAVEL1 (also check-in desk) a place where you go to show your ticket and give in your bags before you get ready to board the plane, train, boat etcWe got to the check-in with plenty of time to spare.2 (also check-in time) the time when you have to arrive and show your ticket, before you get on a plane, train, boat etcCheck-in is at 4 o'clock. 