-A well-read individual; a person with wide knowledge of books.
-One that has comprehensive knowledge of books and bibliography.
-A person who possesses an encyclopedic knowledge of books and bibliography.
-One versed in bibliography or the history of books.
From French bibliognoste, from biblio- + -gnoste (from Greek gnōstēs one who knows, from gignōskein to know).
Used in a sentence:
“Gerald quickly discovered that being a bibliognost was going to come in handy in his new job at the library.”
Bibliognostic - adjective