fair (adj.)youdaoicibaDictYouDict[fair 词源字典]
Old English fæger "pleasing to the sight (of persons and body features, also of objects, places, etc.); beautiful, handsome, attractive," of weather, "bright, clear, pleasant; not rainy," also in late Old English "morally good," from Proto-Germanic *fagraz (cognates: Old Saxon fagar, Old Norse fagr, Swedish fager, Old High German fagar "beautiful," Gothic fagrs "fit"), perhaps from PIE *pek- (1) "to make pretty" (cognates: Lithuanian puošiu "I decorate").

The meaning in reference to weather preserves the oldest sense "suitable, agreeable" (opposed to foul (adj.)). Of the main modern senses of the word, that of "light of complexion or color of hair and eyes, not dusky or sallow" (of persons) is from c. 1200, faire, contrasted to browne and reflecting tastes in beauty. From early 13c. as "according with propriety; according with justice," hence "equitable, impartial, just, free from bias" (mid-14c.).

Of wind, "not excessive; favorable for a ship's passage," from late 14c. Of handwriting from 1690s. From c. 1300 as "promising good fortune, auspicious." Also from c. 1300 as "above average, considerable, sizable." From 1860 as "comparatively good."

The sporting senses (fair ball, fair catch, etc.) began to appear in 1856. Fair play is from 1590s but not originally in sports. Fair-haired in the figurative sense of "darling, favorite" is from 1909. First record of fair-weather friends is from 1736 (in a letter from Pope published that year, written in 1730). The fair sex "women" is from 1660s, from the "beautiful" sense (fair as a noun meaning "a woman" is from early 15c.). Fair game "legitimate target" is from 1776, from hunting.
Others, who have not gone to such a height of audacious wickedness, have yet considered common prostitutes as fair game, which they might pursue without restraint. ["Advice from a Father to a Son, Just Entered into the Army and about to Go Abroad into Action," London, 1776]
[fair etymology, fair origin, 英语词源]
harpy (n.)youdaoicibaDictYouDict
winged monster of ancient mythology, late 14c., from Old French harpie (14c.), from Latin harpyia, from Greek Harpyia (plural), literally "snatchers," which is probably related to harpazein "to snatch" (see rapid (adj.)). Metaphoric extension to "repulsively greedy person" is c. 1400.
In Homer they are merely personified storm winds, who were believed to have carried off any person that had suddenly disappeared. In Hesiod they are fair-haired and winged maidens who surpass the winds in swiftness, and are called Aello and Ocypete; but in later writers they are represented as disgusting monsters, with heads like maidens, faces pale with hunger, and claws like those of birds. The harpies ministered to the gods as the executors of vengeance. ["American Cyclopædia," 1874]
SherlockyoudaoicibaDictYouDict
masc. proper name, literally "fair-haired," from Old English scir "bright" + locc "lock of hair." Slang for "private detective, perceptive person" (the latter often ironic) is attested from 1903, from A.C. Doyle's fictional character Sherlock Holmes (full name in this sense used from 1896; Holmes debuted in 1887 and was popular by 1892).
xanthous (adj.)youdaoicibaDictYouDict
1829, "fair-haired and light-complexioned," from Greek xanthos "yellow," of unknown origin (see xantho-). But the word also was used in 19c. anthropology as "specifying the yellow or Mongoloid type of mankind" [Century Dictionary].