What does plenary discussion mean?

1. (a.) Full; entire; complete; absolute; as, a plenary license; plenary authority.
2. (n.) Decisive procedure.

1.Full, complete.

2. In the courts of admiralty, and in the English ecclesiastical courts, causes or suits in respect of the different course of proceeding in each, are termed plenary or summary. Plenary, or full and formal suits, are those in which the proceedings must be full and formal: the term summary is applied to those causes where the proceedings are more succinct and less formal. Law's Oughton, 41; 2 Chit. Pr. 481.

Source: Bouvier's Law Dictionary, Revised 6th Ed (1856)