something hidden, secret, or invisible. The occult sciences are magic, necromancy, cabala, &c. 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 for a line that is scarce 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, pieces of perspective, &c. They are to be effaced when the work is finished.