The phrase "peak of curve" refers to the highest point on a graph or chart that represents a particular data set. There are several synonyms for this term that may be used interchangeably, depending on the context. One such synonym is "maximum point," which refers to the point on the graph where the data reaches its highest value. Another synonym is "apex," which also refers to the highest point on a graph or curve. The term "crest" may also be used to describe the peak of a curve, while "zenith" refers to the summit or highest point of any object or situation. Lastly, "climax" is another synonym that may be used to describe the point of greatest intensity or highest point of a graph.