Definition of star thistle
1
: a widely naturalized spiny Old World knapweed (Centaurea calcitrapa) with purple flowers
— called also caltrops
2
: any of various knapweeds related to the star thistle
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Merriam-Webster unabridged
Share star thistle
Time Traveler for star thistle
The first known use of star thistle was in 1578
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