westyoudaoicibaDictYouDict[west 词源字典]
west: [OE] Etymologically, the west may be the direction in which the sun goes ‘down’. Together with German and Dutch west, Swedish väster, and Danish vest, it comes from a prehistoric Germanic *westaz. This in turn was descended from the Indo-European base *wes-, which also produced Latin vesper (source of English vespers) and Greek hesperos ‘evening’ and was related to Sanskrit avas ‘down’. French ouest and Spanish oeste were borrowed from English west, Romanian vest from German west.
=> vespers[west etymology, west origin, 英语词源]
westyoudaoicibaDictYouDict
Old English west (adv.) "in or toward the west, in a westerly direction," from Proto-Germanic *west- (cognates: Old Norse vestr, Old Frisian, Middle Dutch, Dutch west, Old High German -west, only in compounds, German west), from PIE *wes-, reduced form of *wes-pero- "evening, night" (cognates: Greek hesperos, Latin vesper "evening, west;" see vesper). Compare also High German dialectal abend "west," literally "evening." French ouest, Spanish oeste are from English.

As an adjective from late 14c.; as a noun from late 12c. West used in geopolitical sense from World War I (Britain, France, Italy, as opposed to Germany and Austria-Hungary); as contrast to Communist Russia (later to the Soviet bloc) it is first recorded in 1918. West Coast of the U.S. is from 1850; West End of London is from 1776; West Side of Manhattan is from, 1858. The U.S. West "western states and territories" originally (1790s) meant those just west of the Alleghenies; the sense gradually extended as the country grew. To go west "die" was "common during the Great War" [OED, 2nd ed.], perhaps from Celtic imagery or from the notion of the setting sun. In U.S. use, in a literal sense "emigrate to the western states or territories," from 1830.