Porcupine reaches Latin porcus, pig, and spina, spine or prickle. The compound travelled through Italian and French before English.
English did not borrow the pieces directly from Latin as a ready-made compound.
Sources
- Merriam-Webster: porcupine
Word History gives the Italian, French and English route; Kids Etymology supplies the Latin component meanings.
- Online Etymology Dictionary: pork
Also from Latin *porcus* "pig": pork (via Old French porc)
- Treccani Vocabolario · porcospino
Meanings of the older forms on the word path.