ogive

n. the somewhat flattened S-shaped curve typically obtained by graphing a cumulative frequency distribution. Consider the example of test results from students in a classroom. Cumulative frequency values would be given along the vertical y-axis and obtained test scores along the horizontal x-axis. The plot would increase slightly at either end, indicating that few students received very low or very high scores, but rise much more steeply in the center, indicating that the majority of students received average scores.