1. Any tree belonging to the genus Ailanthus, of the quassia family, especially A

2. Any of several wide-spreading trees of the genus Ailanthus, of the quassia family, with long leaves and dense flower clusters, esp

3. Ailanthus, Any of the flowering plants that make up the genus Ailanthus, in the quassia family (Simaroubaceae), native to eastern and southern Asia and northern Australia and naturalized in subtropical and temperate regions elsewhere

4. Noun Word forms: plural aiˈlanthuses any tree or shrub of a genus (Ailanthus) of the quassia family, having pointed leaflets, fine-grained wood, and clusters of small, greenish flowers with an unpleasant odor see also tree of heaven Webster’s New World College Dictionary, 4th Edition.