* Curse: This is the most direct opposite of a blessing, signifying misfortune or ill will.
* Malediction: Similar to curse, but often with a more formal or literary tone.
* Imprecation: A verbal curse or invocation of evil.
* Denunciation: A strong condemnation or criticism.
* Scourge: A cause of great suffering or misery.
* Misfortune: A bad or unlucky event.
The best antonym will depend on the specific situation and the intended meaning.