The venerable Antiquarian Bookman (AB), back in 1949, proposed a set of terms which could serve as a standard in mail order and catalogue transactions. A quick search could not locate it, so I reproduced it here, from my printed archives.
As New is to be used only when the book is in the same immaculate condition in which it was published. There can be no defects, no missing pages, no library stamps, etc., and the dustjacket (if it was issued with one) must be perfect, without any tears. (The term As New is preferred over the alternative term Mint to describe a copy that is perfect in every respect, including jacket.)
Fine approaches the condition of As New, but without being crisp. For the use of the term Fine there must also be no defects, etc., and if the jacket has a small tear, or other defect, or looks worn, this should be noted.
Very Good can describe a used book that does show some small signs of wear (but no tears) on either binding or paper. Any defects must be noted.
Good describes the average used and worn book that has all pages or leaves present. Any defects must be noted.
Fair is a 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 must be noted.
Poor describes a book that is sufficiently worn that its only merit is as a Reading Copy because it does have the complete text, which must be legible. 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.
Ex-library copies must always be designated as such no matter what the condition of the book.
Book Club editions must always be noted as such no matter what the condition of the book.
Binding Copy describes a book in which the pages or leaves are perfect but the binding is very bad, loose, off, or nonexistent.
Dustjacket. In all cases, the lack of a dustjacket should be noted if the book was issued with one.