To rebuff someone means to reject them abruptly or bluntly, usually when they're trying to be friendly, helpful, or get your attention. When you rebuff someone, you push them away with words or actions that make it clear you're not interested in what they're offering.

Imagine a new student trying to join a lunch table, and the kids there say “we're full” even though there's clearly room. That's a rebuff. Or picture someone offering to help with a difficult project, and you snap back, “I don't need your help” in an unfriendly tone. The person feels rejected and probably hurt.

A rebuff is harsher than simply saying “no thanks.” It has a cold, dismissive quality that actively pushes someone away. You might politely decline an invitation, but you rebuff someone with force and finality. Politicians rebuff questions from reporters they don't want to answer. A cat might rebuff your attempts to pet it by hissing and swatting.

When you rebuff someone, you're not leaving the door open for later.