What is "occult line"

Occult \Oc*cult"\,

1. [L. occultus, p. p. of occulere to cover up, hide; ob (see Ob-) + a root pro

2. akin to E. hell: cf. F. occulte.] Hidden from the eye or the understanding; invisible; secret; concealed; unknown.

   It is of an occult kind, and is so insensible in its advances as to escape observation.
   --I. Taylor.

   Occult line (Geom.), a line drawn as a part of the construction of a figure or problem, but not to appear in the finished plan.

   Occult qualities, those qualities whose effects only were observed, but the nature and relations of whose productive agencies were undetermined; -- so called by the schoolmen.

   Occult sciences, those sciences of the Middle Ages which related to the supposed action or influence of occult qualities, or supernatural powers, as alchemy, magic, necromancy, and astrology.

n. A line drawn as a part of the construction of a geometrical figure or problem, but not to appear in the finished plan.