opisthogastric
/əˌpɪsθəˈɡastrɪk/adjective
1 Zoology. Designating or situated on the underside (venter) of the opisthosoma of certain mites.
2 Zoology. Relating to or designating an earthworm that has one or more intestinal gizzards.
Origin
Mid 19th century (in an earlier sense). From opistho- + gastric.