There are several synonyms that can be used for the phrase "bristle at". These include "react angrily to", "take offense at", "become upset about", "be irritated by", and "feel indignant towards". When someone "bristles at" something, they are usually reacting defensively to something that has been said or done. For example, someone might bristle at an insensitive comment or a criticism of their work. The use of synonyms allows for more variety in language and can help to convey different levels of emotion or intensity in a particular situation. When writing, it is important to choose the most appropriate synonym based on the tone and context of the piece.