Kiddo/ˈkɪdəʊ/ Definition 1 of 2Pro Tip 1/3Affectionate Term Often used by parents or adults towards kids to show affection or praise. You're making progress, kiddo! Pro Tip 2/3Informal Address Never used in formal situations, best for casual conversations among family or friends. Let's grab some ice cream, kiddo. Pro Tip 3/3Youthful Spirit Can be used endearingly for young-at-heart adults in playful contexts. Hey kiddo, ready for our adventure?