The tongue is read as speech, taste and the power of words to soothe or wound. Biting your tongue stands for restraint; a sharp tongue, harsh words.
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.