Knee jerk reaction is a term usually used to describe an immediate, quick and automatic response to an event or situation. There are several synonyms for this term, including reflex reaction, impulsive response, automatic response, snap judgment, gut reaction, knee-jerk response, and involuntary reaction. These terms describe a kind of response that is often unplanned and not well thought through. These synonyms can be used interchangeably, depending on the context of the situation. Whether it's a reflex reaction, impulsive response, or an automatic reaction, it's important to take a moment to reflect and make a more thoughtful and intentional decision about the situation.