from The Century Dictionary and Cyclopedia
- Having three thorns or a triple thorn.
Sorry, no etymologies found.
The sweet, or honey, locust is another variety, which is also called the three-thorned acacia, because the thorns consist of one long spine with two shorter ones projecting out of it, like little branches, near its base.
A flat and three-thorned blackthorn would lick the scholars out of Dublin town!
(_Liriodendron tulipifera_) -- the water-locust (_Gleditschia monosperma_); and, of the same genus, the three-thorned honey-locust