Bifolio or bifolium (pl. bifolia.) A single sheet of writing material, which, when folded in half creates two folia/leaves, with four pages/sides.
Conjoint face/pages Each bifolium, or sheet, has two sides. Each side, when folded, presents two pages on either side of the fold. As the pages are on a single sheet they can be described as conjoint.
Diptych Two full page miniatures which relate to one another by theme or subject and which occupy facing pages.
Facing pages The two pages facing each other when a book is open.
Folio (pl. folia.) A single sheet of writing material, often half of a bifolium, having two sides. Folia are given a single number referring to both sides, which are then distinguished as either recto or verso by the addition of ‘r’ or ‘v’ after the number: e.g. f. 62v.
Gathering See quire.
Illustrated vita The textual composition of the life of a saint (see Vita), in a manuscript with accompanying illustrations.
Leaf (pl. leaves) See folio.
Miniatures The paintings on a page, regardless of size. They can occupy a single side, or be divided into registers of equal or varying sizes and shapes and can be executed in many colours, a limited palette, or as line drawings.
Page One side of a folio with each folio having two pages (or sides), a recto and a verso.
Psalter A book of psalms.
Quaternion A group of four folded sheets of writing material inserted into each other at the fold (four bifolia, which on folding results in eight folia, sixteen pages or sides). Bifolia grouped in this manner are bound with other quaternions to produce manuscripts.
Quire Two or more bifolia inserted into each other at the fold form a “booklet” termed a quire or gathering. Any number of these booklets stacked together form a book. A quaternion is a quire with a specific number of bifolia (see above).
Recto The side of the folio on the right of facing pages, having the abbreviation ‘r’, as in f. 62r.
Registers Miniatures may be divided into two or more rows each of which constitutes a register.
Verso The side of the folio on the left of facing pages, having the abbreviation ‘v’, as in f. 63v.
Vita The life of a saint. See also Illustrated Vita.
Vita manuscript A manuscript containing a vita.