The noun execration means an angry denouncement or curse. A protester's furious execration of the police might end up getting her arrested.
Use the word execration when you talk about something that's yelled or muttered angrily. When you declare, "May the god Apollo strike you down for saying that!" it's an execration. The person at whom you hurl the execration can also be called an execration, or an object of condemnation. The root word is execrari, which means "to hate or curse" in Latin.