The plural of the English loadword vena cava from Latin is venae cavae. What are the etymological and grammatical reasons for this plural? Why are both words in a single term pluralized? And are there other similar terms in English?
The phrase "vena cava" literally translates from the Latin "hollow (like a cave) vein".
In Romance languages, the adjective is pluralized with the noun, hence "venae cavae".
As for examples of other plural Latin phrases in English; these are rare. The only I find is "almae matres" as the technically correct, but increasingly unused, plural of "alma mater".