Illustration of thistle
plural thistles
1
: any of various composite (see composite entry 1 sense 1b) flowering plants (especially genera Carduus, Cirsium, and Onopordum) that have prickles on their leaves and sometimes on their stems and often have showy heads of tubular, usually purple flowers
also
: any of various other prickly plants
2
often thistle seed plural thistle seeds
: the small black seed of a tropical African herbaceous plant (Guizotia abyssinica) used especially as a source of oil and for bird feed
Cite this Entry
“Thistle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thistle. Accessed 8 Jul. 2026.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
