bestyoudaoicibaDictYouDict[best 词源字典]
best: [OE] Best and better, the anomalous superlative and comparative of good, go back to a prehistoric Germanic base *bat-, which is related to the archaic English boot ‘remedy’ (as in to boot) and meant generally ‘advantage, improvement’. Its comparative and superlative were *batizon and *batistaz, which came into Old English as respectively betera and betest (gradually reduced via betst to best). The term best man originated in Scotland; it has gradually replaced the earlier bride(s)man and groomsman.
=> better, boot[best etymology, best origin, 英语词源]
bootyoudaoicibaDictYouDict
boot: [14] Boot is a comparatively late acquisition by English. It came, either directly or via Old Norse bóti, from Old French bote, whose source is unknown. The modern British sense ‘car’s luggage compartment’ goes back to a 17thcentury term for an outside compartment for attendants on a coach, which may have come directly from modern French botte. The boot of ‘to boot’ is a completely different word. It comes from Old English bōt ‘advantage, remedy’, which can be traced back to a prehistoric Germanic base *bat-, source also of better and best.
=> best, better
best (adj.)youdaoicibaDictYouDict
Old English beste, reduced by assimilation of -t- from earlier Old English betst "best, first, in the best manner," originally superlative of bot "remedy, reparation," the root word now only surviving in to boot (see boot (n.2)), though its comparative, better, and superlative, best, have been transferred to good (and in some cases well). From Proto-Germanic root *bat-, with comparative *batizon and superlative *batistaz (cognates: Old Frisian, Old Saxon, Middle Dutch best, Old High German bezzist, German best, Old Norse beztr, Gothic batists).
The best-laid schemes o' mice an' men
Gang aft agley,
An' lea'e us nought but grief an' pain,
For promis'd joy!

[Burns]
Best-seller as short for "best-selling book" is from 1902, apparently originally in the publishing trade; best friend was in Chaucer (late 14c.). Best girl is first attested 1881, American English; best man is 1814, originally Scottish, replacing groomsman. To be able to do something with the best of them is recorded by 1748.
boot (n.2)youdaoicibaDictYouDict
"profit, use," Old English bot "help, relief, advantage; atonement," literally "a making better," from Proto-Germanic *boto (see better (adj.)). Compare German Buße "penance, atonement," Gothic botha "advantage." Now mostly in phrase to boot (Old English to bote).
superior (adj.)youdaoicibaDictYouDict
late 14c., "higher in position," from Old French superior "higher, upper" (Modern French superieur), from Latin superiorem (nominative superior) "higher," comparative of superus "situated above, upper," from super "above, over" (see super-).

Meaning "higher in rank or dignity" is attested from late 15c.; sense of "of a higher nature or character" is attested from 1530s. Original sense was preserved more strongly in French (as in les étages supérieur "the upper stories"), and in Lake Superior, a loan-translation of French Lac Supérieur, literally "upper lake" (at 600 feet above sea-level it has the highest surface elevation of the five Great Lakes and is the furthest north).
Surprise a person of the class that is supposed to keep servants cleaning his own boots, & either he will go on with the job while he talks to you, as if it were the most natural thing in the world, or else he will explain that the bootboy or scullery-maid is ill & give you to understand that he is, despite appearances, superior to boot-cleaning. If he takes the second course, you conclude that he is not superior to it; if the first, that perhaps he is. [Fowler]
bothyyoudaoicibaDictYouDict
"(In Scotland) a small hut or cottage, especially one for housing farm labourers or for use as a mountain refuge", Late 18th century: obscurely related to Irish and Scottish Gaelic both, bothan, and perhaps to booth.