The smell and aroma of a good book.
The effect the book has on the nostrils as you breathe in the scent of the pages. This word has not achieved OED status yet and as such I suppose is urban slang, but I am sure we Bibliophiles will soon change that.
“There is nothing more amazing than walking into a second hand book shop, the bibliosmia alone is enough to make one weep”
“If anyone ever bottled Eau de Bibliosmia I’d be first in the queue ha ha.”