IPA: /ˌdaɪəˈbɒlɪkli/
KK: /daɪəˈbɑlɪkli/
In a way that is extremely evil or wicked, often suggesting cleverness or cunning.
The villain plotted diabolically to take over the world.
Diabolically → It is formed from "diabolus" (from Greek "diabolos", meaning slanderer or accuser) and the suffix "-ically" (meaning in a manner relating to). The word "diabolically" means in a manner that is characteristic of a devil or evil spirit.
Think of the word 'diabolus' which relates to a slanderer or accuser, and remember that 'diabolically' describes actions that are devilish or evil in nature.