What's the noun for miter? Here's the word you're looking for.
mitre
A covering for the head, worn on solemn occasions by church dignitaries. It has been made in many forms, mostly recently a tall cap with two points or peaks.
The surface forming the bevelled end or edge of a piece where a miter joint is made; also, a joint formed or a junction effected by two beveled ends or edges; a miter joint.