Populus alba po·pu·lu·salba uncommon noun 1. a poplar that is widely cultivated in the United States; has white bark and leaves with whitish undersurfaces Synonymswhite poplarwhite aspenabeleaspen poplarsilver-leaved poplarPopulus alba Related words Broader terms poplar WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.