- Vertex of a solid
- Vertex 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:
[1913 Webster]
(a) (Anat.) The top, or crown, of the head.
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(b) (Anat.) The zenith, or the point of the heavens directly
overhead.
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(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.
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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. [1913 Webster]

{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 {Vertex of a surface of revolution} (Math.), the point in which the axis pierces the surface. [1913 Webster]

*The Collaborative International Dictionary of English.
2000.*