English word renal comes from Latin ren

Detailed word origin of renal

Dictionary entry	Language	Definition
ren	Latin (lat)	(anatomy) kidney. (this term almost always plural in (ancient) Latin. See B. L. Gildersleeve's Pg. 35, Oxford Latin Dictionary Pg. 1614).
renes	Latin (lat)
renalis	Late Latin (LL)
renal	English (eng)	Pertaining to the kidneys.

Words with the same origin as renal