scarletyoudaoicibaDictYouDict[scarlet 词源字典]
scarlet: [13] Scarlet originally denoted a sumptuous sort of cloth, which came in various colours, not just red. Red was evidently the commonest colour, however, for by the 15th century we find the word scarlet being used for ‘red’. It was borrowed from Old French escarlate, but where that came from is not known (some have derived it from Persian saqalāt ‘rich cloth’, but this has not been conclusively established).
[scarlet etymology, scarlet origin, 英语词源]
scarlet (n.)youdaoicibaDictYouDict
mid-13c., "rich cloth" (often, but not necessarily, bright red), from a shortened form of Old French escarlate "scarlet (color), top-quality fabric" (12c., Modern French écarlate), from Medieval Latin scarlatum "scarlet, cloth of scarlet" (also source of Italian scarlatto, Spanish escarlate), probably via a Middle Eastern source (compare Arabic siqillat "fine cloth"), from Medieval Greek and ultimately from Late Latin sigillatus "clothes and cloth decorated with small symbols or figures," literally "sealed," past participle of sigillare, from the root of sign (n.).

In English as the name of a color, attested from late 14c. As an adjective from c. 1300. Scarlet lady, etc. (Isa. i:18, Rev. xvii:1-5) is from notion of "red with shame or indignation." Scarlet fever is from 1670s, so called for its characteristic rash. Scarlet oak, a New World tree, attested from 1590s. Scarlet letter traces to Hawthorne's story (1850). German Scharlach, Dutch scharlaken show influence of words cognate with English lake (n.2).