The Collaborative International Dictionary of English v.0.48:

Storybook \Sto"ry*book`\, n.
   A book containing stories, or short narratives, either true
   or false.
   [1913 Webster]

WordNet (r) 3.0 (2006):

storybook
    n 1: a book containing a collection of stories (usually for
         children)

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "storybook":
   airy, autistic, best seller, book, bound book, classic,
   coloring book, definitive work, dereistic, folio, great work,
   hardback, idealistic, impractical, in the clouds, juvenile,
   juvenile book, limp-cover book, magnum opus, nonbook, notebook,
   novel, opus, opuscule, opusculum, otherworldly, paperback,
   picture book, playbook, pocket book, poetic, prayer book,
   production, psalmbook, psalter, publication, quixotic, romancing,
   romantic, romanticized, serial, sketchbook, soft-cover, songbook,
   standard work, starry-eyed, title, tome, trade book,
   transcendental, transmundane, unpractical, unrealistic, visionary,
   volume, wish-fulfilling, work, writing