slipcase
/ˈslɪpˌkeɪs/
noun
- A protective box or cover that a book or set of books slides into, open on one side to show the spine.
- She stored her favorite novels in a sturdy slipcase to keep them dust-free.
- The collector's edition came in a beautiful slipcase with gold lettering.
- The slipcase for the encyclopedia set was damaged during the move.