RhymeZone: gravamen definitions

Definitions of gravamen:

noun: A grievance complained of.
noun: (Anglicanism) A document sent by the Lower House of Convocation to the Upper House to inform the latter of certain grievances in the church.
noun: The essence or ground of a complaint.
noun: (by extension) The essence or most important aspect of a piece of writing, a point of argument, etc.; the gist.
noun: (obsolete) A formal charge or complaint.

(Definitions from Wiktionary)