headbutt

noun

1. A sharp blow delivered by driving the head into an opponent or object, generally by lowering the head and charging forward or by rapidly tilting the head backward and then forward.

verb

1. (transitive)To deliver a sharp blow by driving the head into an opponent or object.

   “Then he got down on his hands and knees and pretended to headbutt the cat: 'Come on, come on, little ram! Let's see your horns!'”