greatyoudaoicibaDictYouDict[great 词源字典]
great: [OE] The main adjective for ‘large’ in the Anglo-Saxon period was the now virtually obsolete mickle. Great at that time was for the most part restricted in meaning to ‘stout, thick’. In the Middle English period great broadened out in meaning, gradually taking over from mickle, but in modern English has itself been superseded by big and large, and is now used only in reference to non-material things.

Its origins are a problem. It comes from a prehistoric West Germanic *grautaz, which also produced German gross and Dutch groot (source of English groat ‘small coin’ [14], etymologically a ‘big’ or ‘thick’ coin), but it is not clear where *grautaz came from. A resemblance to grit and groats has suggested a common origin in Indo-European *ghrēu- ‘rub, pound’.
=> grit, groat[great etymology, great origin, 英语词源]
great (adj.)youdaoicibaDictYouDict
Old English great "big, tall, thick, stout, massive; coarse," from West Germanic *grautaz "coarse, thick" (cognates: Old Saxon grot, Old Frisian grat, Dutch groot, German groß "great"). If the original sense was "coarse," it is perhaps from PIE root *ghreu- "to rub, grind," but "the connextion is not free from difficulty" [OED]. It took over much of the sense of Middle English mickle, and itself now is largely superseded by big and large except in reference to non-material things.

In the sense of "excellent, wonderful" great is attested from 1848. Great White Way "Broadway in New York City" is from 1901, in reference to brilliant street illumination. The Great Lakes of North America so called from 1747. Great Spirit "high deity of the North American Indians," 1703, originally translates Ojibwa kitchi manitou. The Great War originally (1887) referred to the Napoleonic Wars, later (1914) to what we now call World War I (see world).
"The Great War" -- as, until the fall of France, the British continued to call the First World War in order to avoid admitting to themselves that they were now again engaged in a war of the same magnitude. [Arnold Toynbee, "Experiences," 1969]
Also formerly with a verb form, Old English greatian "to become enlarged," Middle English greaten "to become larger, increase, grow; become visibly pregnant," which became archaic after 17c.