welteryoudaoicibaDictYouDict[welter 词源字典]
welter: [13] Welter was originally a verb, meaning ‘roll about’ (borrowed probably from Middle Dutch welteren, it came ultimately from the Germanic base *wal-, *wel- ‘roll’, source also of English wallet, wallow, waltz, etc, and is distantly related to English involve, revolve, etc). It was first used as a noun in the 16th century, in the sense ‘confusion, turmoil’, but the modern sense ‘confused mass, jumble’ did not emerge fully until the mid 19th century.

The welter of welter-weight [19], which originally meant ‘heavyweight horseman or boxer’, may be the same word, but it is perhaps more likely to have been derived from the verb welt in the sense ‘hit, thrash’. This originally meant ‘provide a shoe with a welt or strip of leather’, and was derived from the noun welt [15], a word of uncertain origin.
=> involve, revolve, volume, wallow, waltz, weld, well[welter etymology, welter origin, 英语词源]
welter (v.)youdaoicibaDictYouDict
"to roll or twist," early 14c., from Middle Dutch or Middle Low German welteren "to roll," from Proto-Germanic *waltijan (cognates: Old English wieltan, Old Norse velta, Old High German walzan "to turn, revolve," German wälzen "to roll," Gothic waltjan "to roll"), from PIE root *wel- (3) "to turn, revolve" (see volvox). Related: Weltered; weltering.
welter (n.)youdaoicibaDictYouDict
1590s, "confusion," from welter (v.). The meaning "confused mass" is first recorded 1851.