A person with expert knowledge of books; a scholar or expert in bibliography and book lore.
From 'biblio-' (book) plus Greek 'gnostos' (known, knowledgeable). The term parallels 'gnostic' and appeared in 19th-century scholarly discourse for those with deep expertise in books and manuscripts.
A 'bibliognost' knows books inside out—their history, rarity, provenance, editions, variants. It's what book collectors, rare book dealers, and obsessive librarians aspire to be, and it sounds much more impressive than 'book expert.'
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