What does it mean to dream about thorn?
A thorn often stands for a small sharp hurt or defence, the prick that guards a flower or the irritation that will not let you forget it.
Four ways to read it
Each reading below comes from a named tradition and a cited source, so you can see where it came from and decide what fits your dream.
Freud
Freud would note the sting and ask what wounding or warding it stood for. A thorn can carry a grievance the waking mind has not pulled out, or a defence set up against being touched. Whether it protected something or simply hurt you may shape the reading.
After Freud, The Interpretation of Dreams (Brill trans., 1913), public domain.Jung
Jung might see the thorn as the guarded edge of something precious, the defence that keeps the tender thing safe. It can speak of a pain that also protects, suffering that fences off a vulnerable part of the self. A bramble may mark an obstacle the psyche must work through to reach what lies beyond.
Jungian concept (our summary).Modern
Under continuity, thorns tend to follow waking thoughts about a small persistent hurt, a sharp word, or a defended feeling. A thicket of them may mirror a situation that feels prickly and hard to move through. Consider what minor wound has been hard to set aside.
Continuity hypothesis (our summary).Mythological
Thorns in many traditions guard what is sacred or asleep, the hedge of brambles that surrounds a hidden treasure or a sleeping figure. They became an emblem of suffering bound up with worth, the crown and the rose alike. So the thorn carries pain, protection, and the price of reaching something precious.
Rosmerta Publishing editorial synthesis (after Brewer; Bulfinch).