Thorns stand for small pains guarding something worth having — the rose behind the prickles. Dream books read being caught in them as irritation, defensiveness or obstacles that sting.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.