1548, "dregs, leavings, muck," especially in East Anglia, "ooze left by flood" (this may be the original sense), perhaps borrowed from M.Du.
sudse "marsh, bog," cognate with O.E.
soden, pp. of
seoþan (see
seethe). Meaning "soapy water" dates from 1581; slang meaning "beer" first attested 1904.