'retromammary' originates from Latin (via New Latin), specifically the prefix 'retro-' and the word 'mammary', where 'retro-' meant 'back(ward)' and 'mamma' meant 'breast'.

'retromammary' was formed as a compound in modern medical English from Latin elements: 'retro-' (Latin) + 'mammary' (from Latin 'mamma' via New Latin), and entered anatomical usage to denote the area behind the breast.

Initially composed simply to denote position ('behind the breast'), the term has remained specialized in anatomy and clinical contexts with essentially the same meaning.