thistle Meaning, Definition & Usage

  1. noun any of numerous plants of the family Compositae and especially of the genera Carduus and Cirsium and Onopordum having prickly-edged leaves

WordNet

This"tle noun
Etymology
OE. thistil, AS. þistel; akin to D. & G. distel, OHG. distila, distil, Icel. þistill, Sw. tistel, Dan. tidsel; of uncertain origin.
Definitions
  1. (Bot.) Any one of several prickly composite plants, especially those of the genera Cnicus, Craduus, and Onopordon. The name is often also applied to other prickly plants.

Webster 1913