"The act of putting someone in prison or the condition of being kept in prison." (CD)
See also: https://dictionary.cambridge.org/us/dictionary/english/imprisonment?q=Imprisonment
The graph displays the other subjects mentioned on the same pages as the subject "Criminal Procedure--Imprisonment". If the same subject occurs on a page with "Criminal Procedure--Imprisonment" more than once, it appears closer to "Criminal Procedure--Imprisonment" on the graph, and is colored in a darker shade. The closer a subject is to the center, the more "related" the subjects are.