\Ver"tex\, n.; pl. {Vertexes}, L. {Vertices}. [L. vertex,
-icis, a whirl, top of the head, top, summit, from vertere to
turn. See {Verse}, and cf. {Vortex}.]
A turning point; the principal or highest point; top; summit;
crown; apex. Specifically:
(a) (Anat.) The top, or crown, of the head.
(b) (Anat.) The zenith, or the point of the heavens directly
    overhead.
(c) (Math.) 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.
Note: The principal vertex of a conic section is, in the
      parabola, the vertex of the axis of the curve: in the
      ellipse, either extremity of either axis, but usually
      the left-hand vertex of the transverse axis; in the
      hyperbola, either vertex, but usually the right-hand
      vertex of the transverse axis.
{Vertex of a curve} (Math.), the point in which the axis of
   the curve intersects it.
{Vertex of an angle} (Math.), the point in which the sides of
   the angle meet.
{Vertex of a solid}, or {of a surface of revolution} (Math.),
   the point in which the axis pierces the surface.