When it comes to expressing a response or rebuttal, there are several synonyms for the phrase "in rejoinder". Some alternatives include "in reply", "in response", "in answer", "in retort", "in counterargument", and "in opposition". These phrases all indicate a reaction to someone else's statement or position, emphasizing the importance of engaging in a dialogue or debate. In using these synonyms, one can convey a strong sense of confidence, assertiveness, and intellectual rigor, demonstrating a willingness to engage in challenging discussions and take on differing viewpoints. Whether in a formal or informal setting, these synonyms can help one express their opposing views on any given topic.