twinyoudaoicibaDictYouDict[twin 词源字典]
twin: [OE] Twin originally meant simply ‘double’, but the specific application to ‘two people born at the same birth’ had already evolved by the end of the Old English period. The word goes back via prehistoric Germanic *twisnaz to Indo- European *dwisno-, a derivative of the base *dwi- ‘double’ (other derivatives formed with the same -n suffix include English between and twine [OE] – etymologically thread of ‘two’ strands).
=> between, twine, two[twin etymology, twin origin, 英语词源]
twin (adj.)youdaoicibaDictYouDict
Old English twinn "consisting of two, twofold, double, two-by-two," from Proto-Germanic *twisnjaz "double" (cognates: Old Norse tvinnr "double, twin," Old Danish tvinling, Dutch tweeling, German zwillung), from PIE *dwisno- (cognates: Latin bini "two each," Lithuanian dvynu "twins"), from *dwi- "double," from root *dwo- "two" (see two). Minneapolis and St. Paul in Minnesota have been the Twin Cities since 1883, but the phrase was used earlier of Rock Island and Davenport (1856).
twin (v.)youdaoicibaDictYouDict
"to combine two things closely, join, couple," late 14c., from twin (adj.). Related: Twinned; twinning. In Middle English, the verb earlier and typically meant "to part, part with, separate from, estrange," etc. (c. 1200), on the notion of making two what was one.
twin (n.)youdaoicibaDictYouDict
c. 1300, from Old English getwinn "double;" getwinnas "twins, two born at one birth," from twinn (see twin (adj.)).