Antiquarian booksellers describe books in a shorthand that has been in use for a long time and is precise once you know it, but opaque if you do not. Below are the terms that appear in the descriptions on this site, and what each of them means.
If a term is not explained here, or an explanation is not clear enough, please write and ask.
Size and structure
8vo (octavo) — the format of the book, meaning the printed sheet was folded three times to give eight leaves, or sixteen pages. It is a description of how the book was made rather than an exact measurement, so a size in millimetres is given alongside it. A small 8vo is at the smaller end of that range.
Leaf, and page — a leaf is a single piece of paper; a page is one side of it. So a leaf is two pages, and a book of 230 leaves has 460 pages. Early books are counted in leaves because that is how they were numbered.
Folio, and foliation — foliation is the numbering of leaves rather than pages, which is usual in books of the sixteenth century. A reference such as fol. cii points to leaf 102, not page 102.
Recto and verso — the front and back of a leaf. Because early books number leaves rather than pages, a full reference distinguishes the two: fol. cii recto is the front of leaf 102, fol. cii verso the back.
Collation — the formal account of what the book physically consists of: its format, its dimensions, how many leaves it has, how they are numbered, and whether any are missing. It is the section to read if you want to know that a copy is complete.
Square brackets, as in [8] — leaves that the printer left unnumbered, usually the preliminary matter at the front. They are counted separately from the numbered sequence.
Printing
Black letter — the dense angular Gothic type used across northern Europe in the fifteenth and sixteenth centuries, before roman type displaced it. It is harder to read than roman type until the eye adjusts.
Woodcut initial — a decorated capital letter printed from a carved wooden block at the opening of a section. Printers reused the same blocks across many books.
Unsigned, of a woodcut — the block carries no mark identifying its cutter. It says nothing about whether anyone has signed the book by hand.
Binding
Calf — calfskin leather, the commonest binding material for European books of this period. It darkens and dries with age.
Boards — the stiff front and back covers, historically wooden or of pasted paper, over which the leather is drawn.
Blind-tooled — decoration impressed into the leather with heated tools without gold. The pattern is visible as texture and shadow rather than as colour.
Fillet — a plain straight line tooled into the leather. A triple-fillet panel is a rectangular frame of three parallel lines.
Raised bands — the ridges running across the spine, formed by the cords the sections are sewn onto. They are structural, not decorative.
Endbands — the small woven bands at the head and tail of the spine, which strengthen the ends of the text block. On worn bindings they are often partly exposed.
Condition
Text block — the body of printed leaves, considered separately from the binding. A book can have a poor binding and an excellent text block, or the reverse, and the two are always described separately.
Worming — small holes or channels left by boring insects. What matters is where it is: worming in a blank margin is cosmetic, worming that touches the text is a defect, and a description should always say which.
Edition and history
First edition thus — the first appearance of a work in this particular form: a new printer, a new setting of type, a new translation or a new arrangement, though the text itself was published earlier. It is a precise claim, and narrower than first edition.
Provenance — the record of who has owned the book, evidenced by inscriptions, bookplates, stamps or later pencilled notes. It is part of what a copy is, and can matter as much as condition.