Retroperitoneal etymology in English

English word retroperitoneal comes from English peritoneal (Of, relating to, or affecting the peritoneum.), English retro-

Dictionary entry	Language	Definition
peritoneal	English (en)	Of, relating to, or affecting the peritoneum.
retro-	English (en)	(informal) in an old-fashioned or old-school way.. Back or backward.. Behind.. In the opposite direction.. Pertaining to an earlier time (for example, in retroactive).
retroperitoneal	English (en)	Located behind the peritoneum.

Retroperitoneal etymology