Being lost for words is read as feeling that runs ahead of language — shock, awe or something that has no name yet. Dream tradition takes it as a sign that an experience is still being taken in.
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.