Tuck up Definition 1 of 3Pro Tip 1/3Care and Comfort Used to express affection and care when putting someone to bed. After the movie, I tucked the kids up and kissed them goodnight. Pro Tip 2/3Nighttime Routine Commonly used when describing regular bedtime habits for children. Every night at 8, it's time to tuck up the little ones. Pro Tip 3/3Warmth and Security Implies creating a cozy and secure sleeping environment. It's chilly tonight, so I really tucked her up well.