Atlas was a titan, he held up the sky and the heavens, for some reason I don't know, he was often shown in pics carrying the earth on his back, hence the term atlas .

I think it's some kind of Greek word or something coming from another language.

I would assume that it's for the same reason a word is called a word. Someone with not much else to do just came up with it.

I think it's named for the Greek God Atlas.

"The origin of the term atlas is a common source of misconception, perhaps because two different mythical figures named 'Atlas' are associated with mapmaking." 1) "King Atlas, a mythical King of Mauretania in Libya, was, according to legend, a wise philosopher, mathematician and astronomer who supposedly made the first celestial globe. It was this Atlas that Mercator was referring to when he first used the name 'Atlas', and he included a depiction of the King on the title-page." 2) "However, the more widely known Atlas is a figure from Greek mythology. He is the son of the Titan Iapetus and Clymene (or Asia), and brother of Prometheus. Atlas was punished by Zeus and made to bear the weight of the heavens and earth on his back." "In works of art, this Atlas is represented as carrying the heavens or the terrestrial globe on his shoulders." "This figure is frequently found on the cover or title-pages of atlases." Source and further information: http://en.wikipedia.org/wiki/Atlas#.22Atlas.22_etymology So Mercator, the person who created the word Atlas for an atlas had another reference as the reference which has become more widely used.

The origin of the term Atlas in itself is no less interesting than the traditional meaning which has come to denote a collection of maps, providing an encyclopedic wealth of information on the land, people and cultures in different parts of the world. One of the legends in this relation state that the land of Mauretania was once ruled by King Atlas who was a great philosopher, mathematician and astronomer who created the first celestial globe. In 1595, the great cartographer Gerardus Mercator first called his collection of maps as an “Atlas” in honour of this legendary king Atlas. Another even more popular legend speaks about the Greek mythological character of Atlas, the son of Titan Iapetus and Oceanid Asia, who was condemned to bear the burden of celestial sphere on his shoulders by the Greek God of Zeus. The legend goes on to state that Heracles approached Atlas, holding the world, and tempted him into collecting the apples of Hesperides by offering a temporary reprieve from the burden of heavens in the meantime. Atlas readily agreed to the same but on returning with the apples he wished to escape his condemned fate, but, understanding his intent well, Heracles used a little tact to leave Atlas holding up the world once again. Yet another version of the same legend says that Heracles instead erected the two Pillars of Hercules, to end the punishment of Atlas, holding world forever. It is suggested that historically, Antonia Lafreri was the first person to associate a collection of maps with the Greek legend of Titan Atlas and from 16th century onwards, any cartographic collection came to be known as Atlas. Commonly, the globe depicted in the caricatures of Atlas holding up the world is mistaken as earth in what is actually supposed to be the celestial sphere.