brownyoudaoicibaDictYouDict[brown 词源字典]
brown: [OE] In Old English, brown meant, rather vaguely, ‘dark’; it does not seem to have become a definite colour word until the 13th century. It comes from West and North Germanic *brūnaz, which probably goes back ultimately to the same Indo-European source (*bheros) as bear, etymologically the ‘brown [that is, dark] animal’. An additional meaning of brown in Old and Middle English, shared also by related words such as Old High German brūn, was ‘shining, glistening’, particularly as applied to weapons (it survives in fossilized form in the old ballad Cospatrick, recorded in 1802: ‘my bonny brown sword’); Old French took it over when it borrowed brun from Germanic, and it is the basis of the verb burnir ‘polish’, from which English gets burnish [14].

Another contribution made by French brun to English is the feminine diminutive form brunette [17]. An earlier Old French variant burnete had previously been borrowed by English in the 12th century as burnet, and since the 14th century has been applied to a genus of plants of the rose family. The term burnet moth is first recorded in 1842.
=> bear, brunette, burnish[brown etymology, brown origin, 英语词源]
brown (adj.)youdaoicibaDictYouDict
Old English brun "dark, dusky," developing a definite color sense only 13c., from Proto-Germanic *brunaz (cognates: Old Norse brunn, Danish brun, Old Frisian and Old High German brun, Dutch bruin, German braun), from PIE *bher- (3) "shining, brown" (cognates: Lithuanian beras "brown"), related to *bheros "dark animal" (compare beaver, bear (n.), and Greek phrynos "toad," literally "the brown animal").

The Old English word also had a sense of "brightness, shining," preserved only in burnish. The Germanic word was adopted into Romanic (Middle Latin brunus, Italian and Spanish bruno, French brun). Brown Bess, slang name for old British Army flintlock musket, first recorded 1785.
brown (n.)youdaoicibaDictYouDict
"brown color," c. 1600, from brown (adj.).
brown (v.)youdaoicibaDictYouDict
c. 1300, "to become brown," from brown (adj.). From 1560s as "to make brown." Related: Browned; browning.