Suds
mid 19th century: of uncertain sense development but perhaps originally denoting the floodwater of the fens; compare with Middle Low German sudde, Middle Dutch sudse ‘marsh, bog’; probably related to seethe.
wiktionary
From the plural of sud, a variant of sod(“a bubbling or boiling”), equivalent to sud + -s. Related to seethe.
etymonline
suds (n.)
1540s, "dregs, leavings, muck," especially in East Anglia, "ooze left by flood" (according to OED this may be the original sense), perhaps borrowed from Middle Dutch sudse "marsh, bog," or related words in Frisian and Low German, cognate with Old English soden "boiled," from Proto-Germanic *suth-, from PIE *seut- "to seethe, boil" (see seethe). Meaning "soapy water" dates from 1580s; slang meaning "beer" first attested 1904. Related: Sudsy.
