As New: Book is without any visible flaws or defects. Book is second hand and may have been read once, but looks new.
Excellent: Second hand Book is clean with no writing or inscriptions, but may have ONE minor defect which will be noted.
Very Good: Second hand Book will be clean, but will show a few minor signs of wear, such as creasing or bumping of cover corners. Any other defects will be noted.
Good: The book cover will have shelf wear, minor creases and the cover corners will be creased or bumped. Older books may have sunlight damage, such as fading to the spine or discoloration or age spotting to the book leaves/edges.
Readable: The Second hand Book will have considerable wear. It is likely to have notes or highlighting.