There are numerous synonyms for the phrase "on the edge" that can be used to describe various emotional or physical states. For instance, "on the verge" is a synonym for someone who is poised to do something significant or who is about to experience a significant event. "At the precipice" is a synonym for someone who is at the brink of something significant or dangerous. Another synonym is "at the brink," describing someone who is a breath away from a significant experience. One can also use "teetering on the brink" to describe someone who is on the verge of a crisis. These synonyms for "on the edge" highlight different aspects of being on the edge and can be used depending on the context of the situation.