occult

OCCULT', a. [L. occultus, occulo; ob and celo, to conceal.]

Hidden from the eye or understanding; invisible; secret; unknown; undiscovered; undetected; as the occult qualities of matter.

The occult sciences are magic, necromancy, &c.

Occult lines, in geometry, are such as are drawn with the compasses or a pencil, and are scarcely visible.