protostome
noun
pro·to·stome ˈprō-tə-ˌstōm 
: any of a major group (Protostomia) of bilateral metazoan animals (such as mollusks, annelids, and arthropods) characterized in typical forms by determinate and spiral cleavage, formation of a mouth and anus directly from the blastopore, and formation of the coelom by splitting of the embryonic mesoderm compare deuterostome
Word History
Etymology
New Latin Protostomia, from prot- + Greek stoma mouth — more at stomach entry 1
First Known Use
1959, in the meaning defined above