betwixt (prep., adv.)youdaoicibaDictYouDict[betwixt 词源字典]
Old English betweox "between, among, amidst, meanwhile," from bi- "by" (see be-) + tweox "for two," from Proto-Germanic *twa "two" + *-isk "-ish." With parasitic -t that first appeared in Old English and became general after c. 1500.[betwixt etymology, betwixt origin, 英语词源]