To headbutt means to strike someone or something forcefully with your forehead. It's exactly what it sounds like: using your head as a battering ram. A goat might headbutt another goat during a dominance contest, or an angry ram might headbutt a fence post.

In human contexts, headbutting is generally considered dangerous and inappropriate. Soccer players sometimes accidentally headbutt each other while both jumping for the ball, which can lead to injuries and penalties. In rare cases, someone might headbutt a door in frustration, which usually results in a headache and regret.

Many animals with thick skulls or horns, like bighorn sheep, use headbutting as their main form of competition. Male bighorn sheep will charge at each other and collide head-on with tremendous force during mating season, their curved horns crashing together in battles that can be heard echoing across canyons.

When used as a noun, a headbutt is the act itself: “The referee gave a red card after the player's headbutt.”