What did the words ULTIMA THULE, mean when first used and how are they used and what do they mean now?

Northernost regions of the world. Specifically an island to the north of that northern island of Britain.


These days it is generally used as a term for a remote fantasy place.|||ultima Thule in medieval geographies denotes any distant place located beyond the "borders of the known world". Sometimes it is used as a proper noun (Ultima Thule) as the Latin name for Greenland when Thule is used for Iceland.