courteous (adj.)youdaoicibaDictYouDict[courteous 词源字典]
mid-14c., earlier curteis (c. 1300), from Old French curteis (Modern French courtois) "having courtly bearing or manners," from curt "court" (see court (n.)) + -eis, from Latin -ensis.

Rare before c. 1500. In feudal society, also denoting a man of good education (hence the name Curtis). Medieval courts were associated with good behavior and also beauty; compare German hübsch "beautiful," from Middle High German hübesch "beautiful," originally "courteous, well-bred," from Old Franconian hofesch, from hof "court." Related: Courteously (mid-14c., kurteis-liche).[courteous etymology, courteous origin, 英语词源]