U V

vertex
A point in three-dimensional space.
vertices
Preferred plural of vertex. See vertex.
viewpoint
The origin of either the eye- or the clip-coordinate system, depending on context. For example, when discussing lighting, the viewpoint is the origin of the eye-coordinate system. When discussing projection, the viewpoint is the origin of the clip-coordinate system. With a typical projection matrix, the eye-coordinate and clip-coordinate origins are at the same location.
view volume
The volume in clip coordinates whose coordinates satisfy the three conditions

w xw
w yw
w zw