boo-boo Share definition Flag 1. A child's term for an injury, usually something minor, like a scrape or bruise. 2. That annoying little cohort of Yogi Bear's. 3. My cat. 1. "Mommy, I fell off my bike and got a boo-boo!" 2. "Heeey, Boo-Boo!" 3. "Boo-Boo, get off the table!" boo-boo by Loki July 2, 2003 Get the boo-boo mug.