noun
spine lettering; title on the spine of a book
Refers specifically to the text printed on the spine of a book, often the title and author.
背文字がかすれて読めなくなった本がある。
I have a book whose spine lettering has worn off and become unreadable.
図書館で背文字だけを頼りに本を探した。
I searched for the book in the library relying only on the spine lettering.