Definition of vertex

• n. - A turning point; the principal or highest point; top; summit; crown; apex.
• n. - The top, or crown, of the head.
• n. - The zenith, or the point of the heavens directly overhead.
• n. - The point in any figure opposite to, and farthest from, the base; the terminating point of some particular line or lines in a figure or a curve; the top, or the point opposite the base.