paperback
noun
[ ˈpeɪpəbak ]
• a book bound in stiff paper or flexible card.
• "the shelves were stacked with well-thumbed paperbacks"
paperback
adjective
• (of a book) bound in stiff paper or flexible card.
• "the paperback edition of her biography"
in paperback
• in an edition bound in stiff paper or flexible card.
• "the novel is now available in paperback"