Definitions

1. noun

a subkingdom of invertebrate animals that includes annelids, brachiopods, and echinoderms, characterized by a body plan in which the anus develops before the mouth

“The protostome subkingdom is distinct from the deuterostome subkingdom in terms of its embryonic development.”

2. adjective

relating to or characteristic of a protostome

“Protostome animals have a distinct body plan that sets them apart from deuterostomes.”