[1] : The Collaborative International Dictionary of English v.0.48

vertex \ver"tex\, 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

   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
see also:
vertexes vertices verse vortex vertex of a curve vertex of an angle 
vertex of a solid vertex of a surface of revolution 

Vertex >> V Words
Vertex, definition of term: Vertex
vertex_pag1.html

Revolution >> R Words
Revolution, definition of term: Revolution
revolution_pag1.html

Surface >> S Words
Surface, definition of term: Surface
surface_pag1.html

Surface Area >> S Words
Surface Area, definition of term: Surface Area
surface+area_pag1.html

Surface Tension >> S Words
Surface Tension, definition of term: Surface Tension
surface+tension_pag1.html

Ruled Surface >> R Words
Ruled Surface, definition of term: Ruled Surface
ruled+surface_pag1.html