What term refers to deep, bitter resentment?

The term "rancor" specifically describes a deep and bitter feeling of resentment or ill-will. This word captures the intensity and lasting nature of negative emotions towards someone, often resulting from past grievances or conflicts. Rancor implies not only a sense of anger but also a grudging, long-standing bitterness that can linger over time, which is why it is the correct choice for describing profound resentment.

The other terms do not convey the same meaning. Raucous refers to making a loud or boisterous noise, which is unrelated to feelings of bitterness. Profound denotes something that is very deep or intense, but it does not specifically pertain to negativity or resentment. Pretentious implies an assumption of importance not warranted by reality, often relating to behavior or attitudes rather than emotions like resentment. Thus, "rancor" stands out as the only term that encapsulates deep, bitter resentment accurately.