Plenary means complete or full. It can be used to describe a meeting that is attended by all members, where every member has an equal say in decision-making processes.
Results of this work are published in peer review journals and were presented by Dr. Dattner at plenary sessions of the Society of Investigative Dermatology. (mindbodygreen.com)
There were no less than 43 full days of plenary sessions for commissioners meeting on their own. (newlawjournal.co.uk)
D. UNDERSTANDING THE CLIMATE SYSTEM AND ITS RECENT CHANGES: This section was addressed in plenary on Wednesday and Thursday with some issues also taken up in informal groups. (enb.iisd.org)