greeneland, maybe, I don't know

Antarctica?

Greenland

Yes, Greenland is the "official" answer.

Here is a list of the largest islands in the world:

https://www.infoplease.com/world/world-geography/large-islands-world

Why isn't Australia considered an island?

Size comparison Greenland/Australia:

https://www.quora.com/Why-is-Australia-considered-a-continent-and-not-an-island

The characteristics of continents are these:

1. Areas of geologically stable continental crust, or cratons, tectonically independent from other continents
2. Biological distinctiveness, with unique animal and plant life
3. Cultural uniqueness
4. Local belief in separate continental status

Obviously, the first two are scientific, and the second two are more subjective.

To elaborate:

• Australia is separated from all other continents by young oceanic crust. Greenland is geologically part of North America.
• Australia has highly distinct plants and animals. Greenland's are largely shared with northern North America.
• Australia is considerably larger than Greenland. If separation is key, then Antarctica should also be considered an island (making Australia second largest).
• Australia has unique, ancient cultures. Greenland's Arctic cultures, while unique, are part of larger North American Arctic culture.
• Everyone agrees that everything smaller than Australia is an island. Australians themselves are divided, and often claim that Australia is both the world's largest island and the world's smallest continent.

So, there are good reasons to assert that Australia is a continent and not an island.

However, it has to be conceded that there can be no definitive answer. The questions only grow more complex when you look at the details: