welter (v.)

"to roll or twist," early 14c., from Middle Dutch or Middle Low German welteren "to roll," from Proto-Germanic *waltijan (source also of 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." Related: Weltered; weltering.

1590s, "confusion," from welter (v.). The meaning "confused mass" is attested by 1851.