A mania or obsession for collecting and possessing books. The term was popularized (and probably coined) by Thomas Frognall Dibdin (1776-1845), an author and bibliographer who made book collecting a fashionable aristocratic hobby in early 19th c. England. Books were sought after, as early as the 16th c., by an increasing number of noblemen, statesmen and intellectuals as fine collections were equated with taste and refinement. Rare, finely printed or richly bound tomes were particularly valuable. By the 19th c. a library of calf or morocco bound volumes was considered the mark of success in business and epitome of the good life.

This, of course, all went to hell as an ideal for 99.9% of the population once a) literacy became wide-spread enough for reading to be considered declassé, b) books became affordable enough for most people to buy them, and finally c) television rendered sustained reading too difficult for most people, thereby turning books into objects of wide-spread suspicion and resentment.
Sources : 1. Bibliomania, or, Book-madness / by Thomas Frognall Dibdin (Bristol : Thoemmes Press ; Tokyo : Kinokuniya Co., 1997)
2. Biblioholism : the literary addiction / Tom Raabe ; with illustrations by Craig McFarland Brown. (Golden, Colo. : Fulcrum Pub., c1991)
3. Bibliomania in the Middle Ages / Frederick Somner Merryweather. (Bristol : Thoemmes Press ; Tokyo : Kinokuniya Co., 1997)