'aortoiliac' is a modern medical compound formed from 'aorta' + 'iliac'. 'Aorta' comes from Greek 'aortē' (ἀορτή) via Latin 'aorta', meaning 'artery', and 'iliac' comes from Latin 'iliacus' (from 'ilium'), meaning 'flank' or 'hip'.

'aortē' (Greek) → Latin 'aorta' → English 'aorta'; Latin 'ilium' → Latin adjective 'iliacus' → English 'iliac'. These elements were combined in medical New Latin/Modern English to form 'aorto-' + 'iliac' → 'aortoiliac'.

Originally component words referred separately to the 'aorta' and to the 'flank/hip' region (ilium); combined in medical usage the compound came to mean specifically 'pertaining to the aorta and the iliac arteries'.