GRE diabolical Definition Extremely evil or cruel; devilish. Example "The villain's diabolical plan threatened to destroy the city." Sign in to save GRE PDF — $25 ← diabetes diagnose → Related words GRE awe GRE smithereens GRE abacus SAT abase GRE abash GRE abate GRE abbreviate GRE abbreviation SAT abdicate SAT abdomen GRE abduct GRE aberrant