The term 'bitterly angry' can be summarized by the word ACRID, which is a five-letter word meaning 'harsh or corrosive in tone'. ACRID is often used to describe a feeling of intense anger or resentment, often accompanied by a sharp, unpleasant taste. It is also used to describe a situation that is filled with hostility and animosity. In other words, ACRID is a perfect way to describe someone who is bitterly angry.