Dictionary.net

• tall European annual with downy gray-green foliage and dense heads of small white flowers followed by hairy pods; naturalized in North America; sometimes a troublesome weed

2006 - WordNet 3.0
By Princeton University

• tall European annual with downy gray-green foliage and dense heads of small white flowers followed by hairy pods; naturalized in North America; sometimes a troublesome weed

2011 - English Dictionary Database
By DataStellar Co., Ltd