Sentence:  We went into Mrs. Monmouth 's library , which had low <WSD>bookshelves</WSD> all along the walls , and above them a Modigliani portrait , a Jackson Pollock twelve feet long , and a gorgeous Miro with a yellow background , that looked like an inscription from a Martian tomb . 
Meaning of the word marked with <WSD> tags:  a shelf on which to keep books