An egghead is a term we use to describe people who are very intelligent or know a lot about something. It's like being a know-it-all, but not in a mean way. These people have spent a lot of time learning and researching, and they have a lot of knowledge to share. Just like how eggs hold all the nutrients and goodness inside them, eggheads hold a lot of information in their head. So remember, it's cool to be an egghead and know a lot about things!