'posterodorsal' originates from New Latin, combining the prefix 'postero-' (from Latin 'posterus') and 'dorsal' (from Latin 'dorsum'), where 'posterus' meant 'coming after, behind' and 'dorsum' meant 'back'.

'posterodorsal' was formed in modern anatomical New Latin by combining Latin-derived elements 'postero-' and 'dorsal'; it entered English medical and anatomical usage without major phonological change as a compound adjective.

Initially coined as a literal compound meaning 'posterior + dorsal' in anatomical descriptions, its use has remained specialized to denote a position that is both posterior and dorsal.