Exorcist
A person who is believed to be able to cast out a demon/the devil.
aberration
a state or condition markedly different from the norm
Pazuzu
The demon who possesses Regan.
abnegation
the rejection of a doctrine
Hatra
A place in the Iranian desert where there are ancient ruins
Talisman
An object that is believed to have magic powers
defunct
no longer in force or use/inactive
Antediluvian
(an item) from before the time of the biblical flood
Subjugate
The act of bringing something under control