Origin: before 900; (v.) Middle English swoghen,Old English swōgan to make a noise; cognate with Old Saxon swōgan,Old English swēgan,Gothic -swōgjan; (noun) Middle English swow,swo(u)gh, derivative of the v.
"to make a moaning or murmuring sound," O.E. swogan, from P.Gmc. *swoganan (cf. O.S. swogan "to rustle," Goth. gaswogjan "to sigh"), from PIE imitative base *(s)wagh- (cf. Gk. echo). The noun is c.1381, from the verb.