Gravamen n. (pl. L. gravamina , E. gravamens) (Law) The grievance complained of; the substantial cause of the action; also, in general, the ground or essence of a complaint. Bouvier.
... defend himself against his critics and to correct some misapprehensions. In temper and style they are admirable, even when they do not convince. They begin by admitting and accounting for that seeming incongruity between the first three and the last two acts, which has always been the gravamen of critical objection to 'Don Carlos'. After this they attempt to show that such a character as Posa might very well have existed in the sixteenth century at the Spanish court. Then we are told that it was not the author's purpose to depict Carlos and Posa as a pair of ideal friends. For ... — The Life and Works of Friedrich Schiller • Calvin Thomas