Def. 1: Literature is any printed matter, e.g. catalogues, holiday prospectuses, text-books, etc.
Def. 2: Literature are all writings in POETRY and PROSE of recognized excellence, valued for their intense, personal, and imaginative expression of life.
Def. 3: Literature is a piece of art. "Writing is not literature unless it gives to the reader a pleasure which arises not only from the things said, but from the way in which they are said."
ad Def. 3: