Terra Australis (Latin for South Land) was a hypothetical continent first posited in antiquity and which appeared on maps between the 15th and 18th centuries. The existence of Terra Australis was not based on any survey or direct observation, but rather on the idea that continental land in the Northern Hemisphere should be balanced by land in the Southern Hemisphere.[1] This theory of balancing land has been documented as early as the 5th century on maps by Macrobius, who uses the term Australis on his maps.[2]

Source: Terra Australis – Wikipedia