A turning point; the principal or highest point; top; summit; crown; apex.
- The highest point; the apex or summit: the vertex of a mountain.
- Anatomy The highest point of the skull.
- Anatomy The top of the head.
- Astronomy The highest point reached in the apparent motion of a celestial body.
- Mathematics The point at which the sides of an angle intersect.
- Mathematics The point on a triangle or pyramid opposite to and farthest away from its base.
- Mathematics A point on a polyhedron common to three or more sides.