Added 10 October 2026 viscum noun Categories: PlantsObscure Words noun ! Definition from WordNet 3.1, Princeton University. More about viscum at Wordnik → Where our words come from → Type genus of the Viscaceae: Old World evergreen shrubs parasitic on many trees including oaks but especially apple trees, poplars, aspens and cottonwoods. Related Words: viscaceaesantalalessantalaceaehydnocarpusflacourtiaceaedovyalismistletoeguttiferae Back to today's word