Of or relating to the vertex; situated at the vertex, apex, or highest point; placed in the zenith, or point in the heavens directly overhead; figuratively, occupying the highest place.Specifically, being in a position or direction perpendicular to the plane of the horizon; upright; plumb.In medicine, of or relating to the vertex, or crown of the head.In zoology and anatomy: Pertaining to or placed on the vertex, or crown of the head; sincipital; coronal: as, vertical stemmata of an insect; vertical eyes of a fish; the vertical crest of some birds is horizontal when not erected.Placed or directed upward or downward; upright or downright; being at right angles with an (actual or assumed) horizon.See circle.In conic sections, a plane passing through the vertex of a cone and through its axis.In perspective, a plane perpendicular to the geometrical plane, passing through the eye, and cutting the perspective plane at right angles.n. A vertical circle, plane, or line.