The deadbolt is the heaviest lock on the door. Dream books read it as a firm decision to keep something out, or as defensiveness that may also be keeping good things away.
Where in your waking life have you met something like this lately?
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.