Arctic and Antarctica

The Arctic Circle currently at roughly 66° north of the Equator,

defines the boundary of the Arctic seas and lands CC BY 3.0, Link

We know the "top of the world" - the northernmost area of the Earth - as that frozen area known as the Arctic. The name comes from an ancient Greek word. 

Arctic comes from the Greek word ἀρκτικός (arktikos), "near the Bear, northern" and from the word ἄρκτος (arktos), meaning bear. It has nothing to do with the Polar Bears found there but refers either to the constellation known as Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere, or to the constellation Ursa Minor, the "Little Bear", which contains the celestial north pole (currently very near Polaris, the current north Pole Star, or North Star).

Ursa Major and Minor are constellations visible only in the Northern Hemisphere.

Ursa Major as depicted in Urania's Mirror,
a set of constellation cards published in London c.1825

Antarctica is etymologically believed to be the land “of no Bear,” however, the Greek is actually “άντιάρκτικός” which translates to “opposite of the Bear.”

People often forget that Antarctica is Earth's southernmost and least-populated continent. Surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. It is the fifth-largest continent, being about 40% larger than Europe. It is mostly covered by the Antarctic ice sheet, with an average thickness of 1.9 km (1.2 mi).

The modern name given to the continent originates from the word antarctic, which comes from Middle French antartique or antarctique ('opposite to the Arctic') and, in turn, the Latin antarcticus ('opposite to the north') which is derived from the Greek.

The Greek philosopher Aristotle wrote in Meteorology about an "Antarctic region" in c. 350 BCE, and the Greek geographer Marinus of Tyre reportedly used the name in his world map from the second century CE. (The map is now lost.) The Roman authors Gaius Julius Hyginus and Apuleius used for the South Pole the romanized Greek name polus antarcticus, from which derived the Old French pole antartike (modern pôle antarctique) attested in 1270, and from there the Middle English pol antartik, found first in a treatise written by the English author Geoffrey Chaucer.