Entomology definition of Dorsum: the upper surface: in Coleoptera; often
confined to meso- and meta-thorax: Odonata; includes mesepisterna
and meso- and meta-thoracic terga: Diptera; upper surface of
thorax, limited by the dorsopleural sutures laterally, the
scutellum posteriorly and the neck anteriorly: Lepidoptera; the
lower or inner margin of the wing.