'posterior-ventral' is a compound formed from Latin-derived elements: 'posterior' (from Latin 'posterus', meaning 'coming after' or 'later') and 'ventral' (from Latin 'venter', meaning 'belly').

'posterior' entered English via Late Latin/Medieval Latin and Middle English as 'posterior'; 'ventral' comes from Neo-Latin 'ventralis' (from Latin 'venter') and entered English as 'ventral'. The compound usage joins the two anatomical adjectives to specify a combined directional descriptor.

Individually, 'posterior' originally meant 'coming after' and 'ventral' referred to the belly; combined, they specifically describe the position that is both toward the rear and toward the belly surface of an organism.