Definition of Thule in US English:

proper noun

• 1A country described by the ancient Greek explorer Pytheas (c.310 BC) as being six days' sail north of Britain, most plausibly identified with Norway. It was regarded by the ancients as the northernmost part of the world.

  Compare with ultima Thule

• 2A culture that existed in Arctic regions from Alaska to Greenland c.500–1400 AD, whose members were the ancestors of the Inuit.

• 3A settlement on the northwestern coast of Greenland, founded in 1910 by the Danish explorer Knud Rasmussen (1879–1933).