check in

Short definition from Wiktionary

Verb

1. 1
   To announce or record one's own arrival at a hotel, airport etc.
2. 2
   To verify a person's information and record their arrival, such as at a hotel, airport, etc.
3. 3
   To contact another person in order to keep the other person informed of one's situation.
4. 4
   To return (a book to a library, source code to a repository, etc.).
5. 5
   To visit in order to see how someone is doing.
6. 6
   To enter solitary confinement at one's own request for protection from other prisoners.
7. 7
   To send somebody to solitary confinement; to make somebody be admitted to solitary confinement.
8. 8
   To integrate new revisions into the public or master version of a file in a version control system.
9. 9
   to tap on, to touch in, to tap in (to use a smartcard to start a public transport journey)

Noun

1. 1
   The act of checking in at a hotel, airport, etc.
2. 2
   The submission of source code or other material to a source control repository.
3. 3
   The act of contacting another person in order to keep them informed of one's situation.