Middle English (in an earlier sense). From Anglo-Norman plener, plenier, pleiner, plainer, planier, etc., and Old French, Middle French plenier (French plénier) full, absolute, consisting of the full number of members (in cort pleniere) from post-classical Latin plenarius complete; compare -ar. Compare post-classical Latin plenaris complete, Old Occitan plenier, Catalan plener, Spanish †llenero, †plenero.