1. to portray or describe someone or something as evil, wicked, or devilish
Usage: chiefly British spelling; American English typically uses 'diabolize'; often used in contexts of unfair characterization or demonization
2. to make something devilish or evil in nature or character
Usage: less common than the first sense

Examples

• The media diabolised the political opponent with exaggerated claims.
• Critics argued that the film diabolised an entire group of people unfairly.
• Historical accounts often diabolise figures from rival nations.
• The campaign sought to diabolise the competitor's record.
• Some religious groups diabolise secular practices they oppose.
• The novel diabolises the antagonist through increasingly dark revelations.