Entry 2 senses Webster, 1913 Satanism /sāt'-ən-ĭzˌ-əm/ · Sa·tan·ism · IPA /ˈseɪtənɪzm/ 01 n. The evil and malicious disposition of Satan; a diabolical spirit. 1. The evil and malicious disposition of Satan; a diabolical spirit.[R.] 2. The worship of Satan.