DJ : Short for dust jacket, a protective and often decorative wrapper, usually made of paper which wraps around the binding of a book.

jacket : Sometimes used as another term for dust jacket, a protective and often decorative wrapper, usually made of paper which wraps around the binding of a book

G- : A term used to denote a condition a slight grade lesser than Good. Good is defined as "describes the average used and worn book that has all pages or leaves present. Any defects must be noted." (Taken from AB Bookman's Weekly).