1. To maintain contact with another person, especially at intervals so as to remain up to date with each other's lives. My old high school friends and I tried keeping in touch once we graduated, but we all started drifting apart once college got underway. Now, make sure you keep in touch. I want to hear all about your time in Paris!

2. An informal parting phrase, especially with someone one isn't likely to see again anytime soon. OK, Deborah, thank you for your audition. Keep in touch! It was so good to see you again, cousin Jeb—keep in touch!