Definition of Barnaby's thistle
: any of several weeds of the genus Centaurea; especially : a European herb (C. solstitialis) adventive in the eastern U.S. and having a winged stem and tomentose leaves
Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Join MWU now and get access to America’s largest dictionary, with:
- 300,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Origin and Etymology of barnaby's thistle
from Barnaby (day), the time of its flowering
Seen and Heard
What made you want to look up Barnaby's thistle? Please tell us where you read or heard it (including the quote, if possible).