Where does “Australasia” come from?

Australasia (English) comes from French Australasie, from Latin australis, from Latin auster, from Proto-Italic *austeros.

Ancestry of “Australasia”, step by step

Step	Language	Word	Meaning
1	French	Australasie	—
2	Latin	australis	southern; Australian; the south pole
3	Latin	auster	The south wind; south
4	Proto-Italic	*austeros	—

Australasia — Etymology, Origin & Word History | Etymology Explorer