This species is characterized by its robust habit and leaves, laminar thin-textured stipules, sessile or subsessile, subcapitate to short, congested-cymose inflorescences with rather well developed bracts, subsessile flowers, lobed calyx limbs 2.5-3 mm long, and funnelform white corollas. The leaves are mostly smooth abaxially, with the secondary and interseondary veins raised but the remaining venation not or hardly visible. The leaves are obtuse to rounded at the apex, sometimes with a short acuminate tip. This species has not been collected frequently.

Palicourea amplissima is generally similar to some other species from the Chocó biogeographic region, in particular Palicourea grandistipula, with longer calyx limbs divided into narrow lobes; in several features also to Palicourea sessmannii and Palicourea gomezii, both of which have prominulous higher-order venation on the leaf undersides and branched inflorescences; and vegetatively to Palicourea diguana though that has very different inflorescences.