noun
lost book; missing book
Refers to a book or written work that has been lost or is no longer extant, often used in historical or bibliographic discussions.
その逸書の内容は、後世の引用から部分的に知られている。
The contents of that lost book are partially known from later citations.
Compound of 逸 (lost, missing) and 書 (book, document). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning of a lost written work.