Australasian is also used as a loose reference to Australia and New Zealand where something applies equally to both or where it is difficult to be sure (for example where you can't decide what someone's accent is).

cf North American

Aus`tral*a"sian (?), a.

Of or pertaining to Australasia; as, Australasian regions.

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n.

A native or an inhabitant of Australasia.

 

© Webster 1913.