"The highest political position in the United States and some other countries, usually the leader of the government." (CD)
The graph displays the other subjects mentioned on the same pages as the subject "United States. President". If the same subject occurs on a page with "United States. President" more than once, it appears closer to "United States. President" on the graph, and is colored in a darker shade. The closer a subject is to the center, the more "related" the subjects are.