Definition of "check in" []

• To announce or record one's arrival at a hotel, airport etc. (verb)
• To contact another person in order to keep the other person informed of one's situation. (verb)
• To return (a book to a library, source code to a repository, etc.). (verb)

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• "In addition to morning classes of interval training, running, yoga, strength training and spinning, "campers" check in regularly with their trainer, attend group discussions and follow customized nutrition plans."
• "Pattie ... do you think you could use your communicator to check in with Tarak?"
• "Parents will be encouraged to append details of this progress check in the "red book" that records their child's vaccinations, creating a combined health and education passport."