Source : Webster's Revised Unabridged Dictionary (1913)

Thistly \This"tly\, a.
   1. Overgrown with thistles; as, thistly ground.

   2. Fig.: Resembling a thistle or thistles; sharp; pricking.

            In such a world, so thorny, and where none Finds
            happiness unblighted, or, if found, Without some
            thistly sorrow at its side.           --Cowper.