Creep is slow, gradual movement that's barely noticeable at first but adds up over time. A glacier creeps down a mountain over centuries, moving so slowly you'd never see it happen if you watched for an hour. Vines creep up the side of a building, adding a little growth each day until suddenly they've covered an entire wall. When you creep down the stairs on Christmas morning, you're moving carefully and quietly, hoping not to wake anyone.

The word can also describe something spreading in an unwanted way. Mission creep happens when a project that started small keeps expanding: you planned to clean your desk, but then you started organizing your whole room, then reorganizing your closet, and suddenly you've spent six hours on what was supposed to be a fifteen-minute task. Scope creep works the same way, when a school project keeps getting bigger and more complicated than originally planned.

As a noun, a creep is someone whose behavior makes others uncomfortable, usually because they ignore normal social boundaries or act in ways that feel intrusive or unsettling. Unlike someone who's simply awkward or shy, a creep keeps doing things that make people want to avoid them, even after others show they're uncomfortable. The word is also used casually to describe someone who's just unpleasant or annoying.