A piece of furniture or a fixture for storing books. Slightly more formal than 本棚 (ほんだな).
書架に並んだ本を眺めるのが好きだ。
I like looking at the books lined up on the bookshelf.
The books are arranged on the library's bookshelves.
I search for materials from the library bookshelves.
He took an old dictionary off the shelf.
書架 is a formal, library-style word for a bookshelf, while 棚 is the everyday general term for any shelf or rack.
stand; base; platform; table; rack · setting (of a gem); mounting · stock (in grafting) · counter for machines and vehicles · level; mark; range; decade (of one's life) · tall building (with a fine view); observation platform · plateau; heights
Compound of 書 (しょ, 'book') and 架 (か, 'shelf, rack').