Outie's counterpart

INNIE

Think of the two types of belly buttons—this one forms a small dip rather than protruding outward.

"Outie" is a casual term for an outwards-bellying navel, so its counterpart is naturally an "innie," the inward-dipping belly button. The clue plays on the simple opposite pairing, like "up" and "down" or "hot" and "cold." It’s a straightforward reference to the two common types of navels, with no hidden wordplay—just a direct contrast. Most people recognize the terms from everyday language about body features.