A biennial Eurasian thistle (Cirsium vulgare) in the composite family, naturalized in North America and having heads of purplish flowers and spiny stems and leaves.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.