Half straight and half round, D is read as a meeting of firmness and softness. As a low grade it can echo the fear of falling short; for many it is also the first letter of a significant name.
Does the traditional reading fit your dream, or did it mean something else to you?
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.