ple ‧ na ‧ ry /ˈpliːnəri/ BrE AmE adjective [only before noun] formal
[ Date: 1500-1600 ; Language: Late Latin ; Origin: plenarius , from Latin plenus ; ⇨ ↑ plenty 3 ]
1 . involving all the members of a committee, organization etc:
The conference ended with a plenary debate.
2 . plenary powers are complete powers with no limit:
He was given plenary powers to negotiate with the rebels.
—plenary noun [countable]