The Collaborative International Dictionary of English v.0.48:
Satanism \Sa"tan*ism\, n. 1. The evil and malicious disposition of Satan; a diabolical spirit. [R.] [1913 Webster] 2. The worship of Satan. [PJC]WordNet (r) 3.0 (2006):
Satanism n 1: a belief in and reverence for devils (especially Satan) [syn: diabolism, demonism, Satanism]