noun
book cover; folding book case
Refers to a traditional protective case for books, often a folding box with clasps, used historically for scrolls or bound volumes. Rare in everyday modern Japanese.
古い経典は帙に収められていた。
The old sutras were kept in a folding book case.
counter
counter for book covers
Used as a counter for book covers or cases, especially in bibliographic or antiquarian contexts. Extremely specialized and not used in ordinary counting.
この文庫には帙が三つある。
This collection has three book cases.