nobleyoudaoicibaDictYouDict[noble 词源字典]
noble: [13] Etymologically, to be noble is simply to be ‘well known’. The word reached English via Old French noble from Latin nōbilis. But this was only a later form of an original gnōbilis (preserved in the negative form ignoble [16]), which was derived from the base *gnō- ‘know’, source also of English notorious. It thus originally meant ‘knowable’, hence ‘known’, and only subsequently broadened out via ‘well known’ to ‘noble’ (which in ancient Rome denoted ‘belonging to a family of which many members had held high office in the state’).
=> cognition, ignoble, know, notorious, recognize[noble etymology, noble origin, 英语词源]
noble (adj.)youdaoicibaDictYouDict
c. 1200, "illustrious, distinguished; worthy of honor or respect," from Old French noble "of noble bearing or birth," from Latin nobilis "well-known, famous, renowned; excellent, superior, splendid; high-born, of superior birth," earlier *gnobilis, literally "knowable," from gnoscere "to come to know," from PIE root *gno- "to know" (see know). The prominent Roman families, which were "well known," provided most of the Republic's public officials.

Meaning "distinguished by rank, title, or birth" is first recorded late 13c. Sense of "having lofty character, having high moral qualities" is from c. 1600. A noble gas (1902) is so called for its inactivity or intertness; a use of the word that had been applied in Middle English to precious stones, metals, etc., of similar quality (late 14c.), from the sense of "having admirable properties" (c. 1300).
noble (n.)youdaoicibaDictYouDict
"man of rank," c. 1300, from noble (adj.). The same noun sense also is in Old French and Latin. Late 14c. as the name of an English coin first issued in reign of Edward III.