Because it's an island situated away from other continents..
Antarctica is the only continent that is not surrounded by other continents. It is isolated by the Southern Ocean.
Antarctica is a continent that does not touch any other continents, as it is surrounded by the Southern Ocean. Australia is another continent that does not share a land border with any other continent.
Australia and Antarctica are the two continents that do not touch any other continent.
Antarctica and Australia.
Antarctica is the continent that is not touching any other continent. It is isolated by the Southern Ocean.
Neither Australia nor Antarctica are connected to any other continent or country.
Australia, who is fully in the Eastern Hemisphere, does not border any other continents. Antarctica, who is partially in the Eastern Hemisphere, does not border any other continents as well.
Australia and Antarctica are the two continents that do not touch any other continents directly. They are both isolated and surrounded by oceans.
Antarctica is the only continent not connected to any other continent.
Australia and Antarctica are the two continents that do not touch any other body of land. They are both isolated by vast oceans, with Australia being surrounded by the Indian and Pacific Oceans, and Antarctica being surrounded by the Southern Ocean.
The seven continents are all made up of several different countries, excepting two: Australia and Antarctica. In the case of Australia, Australia belongs to Australia. Antarctica is not claimed by any country. In the case of all the other continents, no one country holds possession of the whole continent.
Neither Australia nor Antarctica have land borders with other continents, and whether Antarctica is inhabited or not (only a few hundred to a few thousand scientists) is a matter of semantics.