Which term would you use to refer to a strong, bitter animosity?

The term that refers to a strong, bitter animosity is best captured by "acrimony." This word describes feelings of intense hostility or resentment, often manifesting in sharp, bitter interactions between individuals or groups. It effectively conveys the idea of deep-seated ill will, making it appropriate in contexts where there is significant conflict or tension.

In contrast, "amity" denotes a friendly relationship, which is the opposite of animosity. "Tranquility" refers to a state of peace and calmness, lacking any indication of bitterness or hostility. "Ecstasy" signifies an intense feeling of joy or pleasure, which is also unrelated to animosity. Therefore, "acrimony" is the only term that accurately represents the concept of strong, bitter animosity.