Poplar \Pop"lar\, n. [OE. popler, OF. poplier, F. peuplier, fr. L. populus poplar.] (Bot.) 1. Any tree of the genus {Populus}; also, the timber, which is soft, and capable of many uses. Note: The aspen poplar is {Populus tremula} and {P. tremuloides}; Balsam poplar is {P. balsamifera}; Lombardy poplar ({P. dilatata}) is a tall, spiry tree; white poplar is {Populus alba}. 2. The timber of the tulip tree; -- called also {white poplar}. [U.S.]