something hidden, secret, or invisible. The occult sciences are magic, necromancy, and some others. Occult qualities, in philosophy, were those qualities of body or spirit which baffled the investigation of philosophers, and for which they were unable to give any reason. Unwilling, however, to acknowledge their ignorance, they deceived themselves and the vulgar by an empty title, calling what they did not know occult.

Geometry, is used to signify a line that is scarcely perceptible, drawn with the point of the compasses or a leaden pencil. These lines are used in several operations, as the raising of plans, designs of building, and pieces of perspective; and they are to be effaced when the work is finished.