irrefragable (adj.)youdaoicibaDictYouDict[irrefragable 词源字典]
"that cannot be refuted," 1530s, from Late Latin irrefragabilis, from assimilated form of in- "not, opposite of" (see in- (1)) + Latin refragari "to oppose, contest," from re- "back" (see re-) + frag-, base of frangere "to break" (see fraction). Related: irrefragably; irrefragability.[irrefragable etymology, irrefragable origin, 英语词源]