Gypsum becomes plaster, the material of casts and walls, so dream books read it as repair, support and something being set in shape while it heals.
Has this come up in your dreams before? What was going on in your life then?
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.