noun
pocket-size book; pocket edition
Refers to a small-format book designed to be easily carried, often a compact edition of a larger work.
旅行中に読むために、その小説の袖珍本を買った。
I bought a pocket edition of the novel to read during the trip.
袖珍 literally means 'sleeve treasure', referring to a book small enough to be carried in one's sleeve. The term is of Chinese origin and was adopted into Japanese for pocket-size books.