Imaginary points

(Geom.) points, lines, surfaces, etc., imagined to exist, although by reason of certain changes of a figure they have in fact ceased to have a real existence.

See also: Imaginary

References in classic literature ?
Pocket"--for so the man familiarly addressed the imaginary point above him on the slope, crying out:
After a while, he picked up his pencil and began to connect the imaginary points with delicate lines.
But in this case the ordinary people are purely imaginary points of reference.