orthocenter

The point of intersection of the three altitudes of a triangle.

The cointersection point of the straight lines through the three vertexes of a triangle perpendicular to the opposite sides.

That point in which the three perpendiculars let fall from the angles of a triangle upon the opposite sides, or the sides produced, mutually intersect.

: the intersection of the three lines that can be drawn flowing from the three corners of a triangle to a point along the opposite side where each line intersects that side at a 90 degree angle; in an acute triangle, it is inside the triangle; in an obtuse triangle, it is outside the triangle.