Old English Carles wægn, a star-group associated in medieval times with Charlemagne, but originally with the nearby bright star Arcturus, which is linked by folk etymology to Latin Arturus "Arthur." Which places the seven-star asterism at the crux of the legendary association (or confusion) of Arthur and Charlemagne. Evidence from Dutch (cited in Grimm, "Teutonic Mythology") suggests that it might originally have been Woden's wagon. More recent names for it are the Plough (by 15c., chiefly British) and the Dipper (1833, chiefly American).
It is called "the Wagon" in a Mesopotamian text from 1700 B.C.E., and it is mentioned in the Biblical Book of Job. The seven bright stars in the modern constellation Ursa Major have borne a dual identity in Western history at least since Homer's time, being seen as both a wagon and a bear: as in Latin plaustrum "freight-wagon, ox cart" and arctos "bear," both used of the seven-star pattern, as were equivalent Greek amaxa (Attic hamaxa) and arktos.
The identification with a wagon is easy to see, with four stars as the body and three as the pole. The identification with a bear is more difficult, as the figure has a tail longer than its body. As Allen writes, "The conformation of the seven stars in no way resembles the animal,--indeed the contrary ...." But he suggests the identification "may have arisen from Aristotle's idea that its prototype was the only creature that dared invade the frozen north." The seven stars never were below the horizon in the latitude of the Mediterranean in Homeric and classical times (though not today, due to precession of the equinoxes). See also arctic for the identification of the bear and the north in classical times.
A variety of French and English sources from the early colonial period independently note that many native North American tribes in the northeast had long seen the seven-star group as a bear tracked by three hunters (or a hunter and his two dogs).
Among the Teutonic peoples, it seems to have been only a wagon, not a bear. A 10c. Anglo-Saxon astronomy manual uses the Greek-derived Aretos, but mentions that "unlearned men" call it "Charles's Wain":
Arheton hatte an tungol on norð dæle, se haefð seofon steorran, & is for ði oþrum naman ge-hatan septemtrio, þone hatað læwede meon carles-wæn. ["Anglo-Saxon Manual of Astronomy"]
[Septemtrio, the seven oxen, was yet another Roman name.] The star picture was not surely identified as a bear in English before late 14c.
The unlearned of today are corrected that the seven stars are not the Great Bear but form only a part of that large constellation. But those who applied the name "Bear" apparently did so originally only to these seven stars, and from Homer's time down to Thales, "the Bear" meant just the seven stars. From Rome to Anglo-Saxon England to Arabia to India, ancient astronomy texts mention a supposed duplicate constellation to the northern bear in the Southern Hemisphere, never visible from the north. This perhaps is based on sailors' tales of the Southern Cross.