Tween/twiːn/ Definition 1 of 3Pro Tip 1/3Age Specific Refers to children aged around 10-12, not younger kids or older teens. Her tween brother just started middle school. Pro Tip 2/3Development Stage Indicates a stage where children start developing interests beyond childhood. Tweens often start to explore new hobbies. Pro Tip 3/3Growth Transition Marks the transition phase in growth, behavior, and interests. Tween years are when many kids get their own cell phones.