1. supernatural, mystical or magical powers, practices, or phenomena.

adjective

1. involving or relating to supernatural, mystical, or magical powers,
   practices, or phenomena.
2.  In medicine: (of a disease or process) not accompanied by readily discernible signs or symptoms.

“I don’t hold with paddlin’ with the occult,”
said Granny firmly.
“Once you start paddlin’ with the occult
you start believing in spirits,
and when you start believing in spirits
you start believing in demons,
and then before you know where you are
you’re believing in gods.
And then you’re in trouble.”
“But all them things exist,”
said Nanny Ogg.
“That’s no call to go around believing in them.
It only encourages ’em.” 
(Terry Pratchett, Lords and Ladies)

• https://www.holidayinsights.com/moreholidays/November/occultday.htm