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.
The top, or crown, of the head.
The zenith, or the point of the heavens directly overhead.
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.
⇒ 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, ∨ of a surface of revolution Math., the point in which the axis pierces the surface.
© Webster 1913.