The broad-billed parrot's head was large in proportion to its body, and there was a distinct crest of feathers on the front of the head. The bird had a very large beak, comparable in size to that of the hyacinth macaw, which would have enabled it to crack hard seeds. Subfossil bones indicate that the species exhibited greater sexual dimorphism in overall size and head size than any living parrot. The exact colouration is unknown, but a contemporary description indicates that it had multiple colours, including a blue head, and perhaps a red body and beak. It is believed to have been a weak flier, but not flightless.