'austroriparian' is a modern English formation combining the prefix 'austr-' (from Latin 'australis' or 'Auster') meaning 'southern' and 'riparian' (from Latin 'ripa' via 'riparius') meaning 'river bank'.

'riparian' developed from Latin 'ripa' → Medieval Latin 'riparius' → Middle English/Modern English 'riparian'. The element 'austr-' comes from Latin 'australis' (or the name of the south wind 'Auster'); in modern English these elements were joined to coin 'austroriparian'.

The component parts originally meant 'southern' and 'river bank' respectively; over time they have been combined in modern usage to mean 'relating to the southern bank of a river'.