from the GNU version of the Collaborative International Dictionary of English
- n. A European composite herb (Centaurea nigra); -- so called from the resemblance of its knobbed head to an iron ball fixed on a long handle.
from The Century Dictionary and Cyclopedia
- n. The knapweed, Centaurea nigra: so called in reference to the knobbed involucres.
Sorry, no etymologies found.
They fabricate likewise all such iron implements as they use very artificially; such as the heads of their darts, fish-hooks, _hooking_ irons, _ironheads_, and great daggers, some of these last being as long as a bill hook, or woodcutters knife, very sharp on both sides and bent like a Turkish cymeter, and most of the men have such a dagger hanging on their left side.