IPA: /dɪˈmoʊniˌækli/
KK: /dɪˈmoʊniˌækli/
In a way that is related to or characteristic of a demon; often suggesting evil or wickedness.
The villain laughed demoniacally as he plotted his revenge.
Demoniacally → It is formed from "demon" (from Greek "daimon", meaning spirit or divine power) and "-iac" (a suffix used to form adjectives indicating a relation to a specified subject) combined with "-ally" (meaning in a manner). The word describes something done in a manner relating to or characteristic of a demon.
Think of the word 'demon' as relating to a spirit or evil force, and remember that 'demoniacally' means acting in a way that is characteristic of a demon.