accidental point

Wiktionary

1. n. perspective A point on the horizon at which two parallel lines appear to meet.

GNU Webster's 1913

1. adj. (Persp.) the point in which a right line, drawn from the eye, parallel to a given right line, cuts the perspective plane; so called to distinguish it from the principal point, or point of view, where a line drawn from the eye perpendicular to the perspective plane meets this plane.