swamp

Early attestations (starting in 1624) are from North America, but the term was probably in local use in Britain earlier. The etymology is not entirely certain; it is probably a fusion of Middle English swam (“swamp, muddy pool, bog, marsh”, also “fungus, mushroom”) — from Old English swamm (“mushroom, fungus, sponge”), from Proto-West Germanic *swamm, from Proto-Germanic *swambaz, *swammaz — and Middle English sompe (“marsh, morass”), from either Middle Dutch somp, sump (“marsh, swamp”) or Middle Low German sump (“marsh, swamp”) (from Old Saxon *sump (“swamp, marsh”)), both from Proto-West Germanic *sump, from Proto-Germanic *sumpaz. *Swambaz, *swammaz and *sumpaz are likely related to each other, but it is unclear whether they are of Indo-European origin or are substrate words or wanderworts.

The word has alternatively been suggested to be a borrowing from Dutch zwamp (“swamp, marsh, fen”). Other cognates include Middle Low German swamp (“sponge, mushroom”), Dutch zomp (“swamp, lake, marshy place”), German Low German Sump (“swamp, bog, marsh”), German Sumpf (“swamp”), Swedish sump (“swamp”). Related also to Dutch zwam (“fungus, punk, tinder”), German Schwamm (“mushroom, fungus, sponge”), Swedish svamp (“mushroom, fungus, sponge”), Icelandic svampur, sveppur (“fungus”), Gothic 𐍃𐍅𐌿𐌼𐍃𐌻 (swumsl, “a ditch”). Related to sump, swim.