swamp gum noun 9forms 1 noun9 •Any of various species of Eucalyptus native to Australia.Two years before, under the swamp-gum in their Mosman garden, away from the children's ears, they had talked of separating […]. — 1983 •Eucalyptus bensonii (mountain swamp gum) •Eucalyptus camphora (mountain swamp gum) •Eucalyptus ovata •Eucalyptus regnans •Eucalyptus rudis •Either of two species of Nyssa native to the southeast United States. •Nyssa aquaticus (water tupelo) •Nyssa biflora (swamp tupelo) formsswamp gums