rotund (adj.)youdaoicibaDictYouDict[rotund 词源字典]
1705, from Latin rotundus "rolling, round, circular, spherical, like a wheel," from rota "wheel" (see rotary). Earlier was rotound (1610s); rotounde (early 15c.). Meaning "full-toned style of oratory" (1830) is after Horace's ore rotundo in "Poetics."[rotund etymology, rotund origin, 英语词源]