Prominence

In topography, prominence (also referred to as autonomous height, and shoulder drop in US English, and drop in British English) is the relative height of a mountain or hill's summit relative to the lowest contour line encircling it but containing no higher summit within it. It is a measure of the independence of a summit. The key col ("saddle") around the peak is a unique point on this contour line and the parent peak (if any) is some higher mountain, selected according to various criteria.