diabolical
UK: ˌdaɪəˈbɒlɪkəl | US: ˌdaɪəˈbɑːlɪkəl
adj. extremely evil or cruel; devilish
adj. (informal) outrageously bad or annoying
diabolical = diabol<devil> + ical<adjective suffix>
- diabol (from Greek diabolos "devil, slanderer," from dia- "across" + ballein "to throw") → implies malicious intent or deception.
 - ical (adjective-forming suffix from Latin -icalis) → denotes "relating to" or "characterized by."
 
Etymology Origin:
The word traces back to Greek diabolos, meaning "slanderer" or "accuser," later adopted into Latin as diabolicus ("devilish"). The root diabol- reflects the concept of "throwing across" (accusations or evil), evolving into its modern sense of extreme wickedness. The suffix -ical standardizes it as an adjective, emphasizing a devilish quality.
The villain's diabolical plan involved trapping the entire city.
Her diabolical laughter sent chills down their spines.
The dictator was known for his diabolical treatment of prisoners.
(Informal) This diabolical traffic made me an hour late!
The puzzle's diabolical difficulty frustrated even the experts.