{ De‐mo″ni‐ac (?), Dem′o‐ni″a‐cal (?; 277), } a. [L. daemoniacus, fr. daemon; cf. F. démoniaque. See Demon.] 1. Pertaining to, or characteristic of, a demon or evil spirit; devilish; as, a demoniac being; demoniacal practices.
Sarcastic, demoniacal laughter. Thackeray.
2. Influenced or produced by a demon or evil spirit; as, demoniac or demoniacal power. “Demoniac frenzy.” Milton.