A lab coat stands for expertise and objectivity. Dream books read it as the wish to approach something rationally, or as feeling studied by someone who holds the authority.
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.