Is the Book a First Edition or not? How to tell a First Edition and a First Edition, First Printing
‚ÄčThere are some helpful online guides to this very complicated area:

Technical Words for the Condition of a Book
A very helpful brief reference for book terms is on the Abebooks website:
It is important to note that certain sellers and sites use different words, use the same terms in different ways and sometimes make up their own words to describe book condition. This can be very confusing.
The eBay site uses different words from those below to describe books for sale and care needs to be taken – you can ask a seller for more information and book images if the images on site aren’t clear.

Terms from the Abebooks site are below:
A Guide to Book Conditions
When considering the purchase of a book for your collection, the condition and, if applicable, the dust jacket, are the most important factors affecting the value.  It pays to become familiar with the basic descriptive terms used by used and rare booksellers to communicate a particular book’s condition.
General Terms
The definitions below are for reference only. Booksellers use these terms, as well as unique terms not included in this list, based on their own criteria. If you would like clarification on any term in a particular seller's description, please contact the bookseller directly for further information.
As New:  The book is in the same immaculate condition as when it was published.  This could be the description for a book that has been lost in a warehouse for years, never shelved, thumbed or even opened yet may still be some years old.
Fine (F or FN): A Fine book approaches the condition of As New, but without being crisp.  The book may have been opened and read, but there are no defects to the book, jacket or pages. 
Very Good (VG): Describes a book that shows some small signs of wear - but no tears - on either binding or paper. Any defects should be noted by the seller.
Good (G): Describes the average used worn book that has all pages or leaves present. Any defects should be noted by the seller.
Fair: Worn book that has complete text pages (including those with maps or plates) but may lack endpapers, half-title, etc. (which must be noted). Binding, jacket (if any), etc., may also be worn. All defects should be noted.
Poor: Describes a book that is sufficiently worn.  Any missing maps or plates should still be noted. This copy may be soiled, scuffed, stained or spotted and may have loose joints, hinges, pages, etc.
Binding Copy: describes a book in which the pages or leaves are perfect but the binding is very bad, loose, off, or nonexistent.
Reading Copy: A copy usually in poor to fair condition that includes all text presented in a legible fashion.  The copy is fine to read but nothing more.
Other Book Terms
Bowed - A condition of the covers or boards of a hard cover book. Bowed covers may turn inward toward the leaves or outward away from the leaves. The condition generally results from a rapid change in the level of moisture in the air and is caused by different rates of expansion or contraction of the paste-down and the outer material covering the board.
Chipped - Used to describe where small pieces are missing from the edges of the boards or where fraying has occurred on a dust jacket or the edge of a paperback.
Dampstained - A light stain on the cover or on the leaves of a book caused by moisture such as a piece of food or perspiration. Generally not as severe as water stains.
Darkening or Fading - When book covers are exposed to light, the colour darkens or becomes more intense. See also tape shadow
Edgeworn - Wear along the edges of hardback book covers.
Ex-library – the book was once owned by, and circulated in, a public library.  This book could well be in any of the above general categories but more often than not has been well used.  May have library stickers, stamps or markings.  Any former library book must be marked ex-library.
Foxed Foxing- Brown spotting of the paper caused by a chemical reaction, generally found in 19th century books, particularly in steel engravings of the period.
Loose - The binding of a new book is very tight; that is, the book will not open easily and generally does not want to remain open to any given page. As the book is used, the binding becomes looser until a well-used book may lay flat and remain open to any page in the book.
Made-up Copy - A copy of a book whose parts have been assembled from one or more defective copies.
Price Clipped - The price has been clipped from the corner of the dust jacket.
Re-backed - A book that has been repaired by replacing the spine and mending the hinges
Re-cased - A book that has been glued back into its covers after having been shaken loose.
Re-jointed - Means the book has been repaired preserving the original covers, including the spine.
Shaken - An adjective describing a book whose pages are beginning to come loose from the binding.
Shelf Wear - The wear that occurs as a book is placed onto and removed from a shelf. It may be to the tail (bottom) edge of the covers as they rub against the shelf, to the dust jacket or exterior of the covers (when no dust jacket is present) as the book rubs against its neighbours, or to the head of the spine which some use to pull the book from the shelf.
Sunned - Faded from exposure to light or direct sunlight.
Tight - The binding of a new book is very tight; that is, the book will not open easily and generally does not want to remain open to any given page. As the book is used, the binding becomes looser until a well-used book may lay flat and remain open to any page in the book.
Trimmed - An adjective indicating that the pages have been cut down to a size smaller than when originally issued.
Unopened - The leaves of the book are still joined at the folds, not slit apart.
Working copy – Even more damaged than a reading copy, the working copy will have multiple defects and may even need repair.
Worming, Wormholes - Small holes resulting from bookworms (the larvae of various beetles.)