GNU Collaborative International Dictionary of English
Found one definition
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Vertex , n.; pl. E. 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: --1913 Webster
(a) (Anat.) The top, or crown, of the head.
1913 Webster(b) (Astron.) The zenith, or the point of the heavens directly overhead.
1913 Webster(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.
1913 Webster☞ 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.
1913 WebsterVertex 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 Vertex of a surface of revolution (Math.), the point in which the axis pierces the surface.
1913 Webster