Synonyms for Hardbound:

n.

pop up, bookends, bookrest, loose-leaf, fiction, encyclopedic, bookmark, bound, encyclopaedic. hardbound (noun)
hardback, hardcover, hardbacked, backed.

Other synonyms:

bookrest, loose-leaf, bookends. encyclopedic, bookmark. pop up, bound. Other relevant words:
encyclopedic, bound, loose-leaf, bookmark, bookrest.