Look up slipcase in Wiktionary, the free dictionary.
A slipcase is a four or five-sided box, usually made of high-quality cardboard, into which binders, books or book sets are slipped for protection, leaving the spine exposed. Special editions of books are often slipcased. A few publishers, such as the Folio Society, have made a point of publishing all their works in fine slipcases.
Protective slipcases may be issued for cassettes, compact discs or DVDs instead of or in addition to the more common jewel cases or DVD keep case, and may be chosen for aesthetic or economic reasons. Larger slipcases that are designed to house one or more jewel cases or DVD keep cases are often used in packaging for special edition releases of CDs or DVDs.