n. a corner of a page turned down to mark a place. [ WordNet 1.5 ]

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. 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 ]