The Collaborative International Dictionary of English v.0.48:

dog-eared \dog"-eared`\, a.
   1. Having the corners of the leaves turned down and soiled by
      careless or long-continued usage; -- said of a book; as,
      an old book with dog-eared pages.

   Note: Making a page dog-eared is sometimes done deliberately
         to mark a location in a book.
         [1913 Webster]

               Statute books before unopened, not dog-eared.
                                                  --Ld.
                                                  Mansfield.
         [1913 Webster]

   2. worn down, shabby.

   Syn: eared.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dog-eared
    adj 1: worn or shabby from overuse or (of pages) from having
           corners turned down; "a somewhat dog-eared duke...a bit
           run down"-Clifton Fadiman; "an old book with dog-eared
           pages" [syn: dog-eared, eared]