The term used in Michael's mathematical treatise for the Venetian silver grosso coin. Pl. denari.

A gold Venetian coin, also used as a currency denomination throughout Europe in Michael's time.

Eastern Roman Empire
The Greek-speaking half of the Roman Empire, also called the Byzantine Empire. (See Byzantine Empire)

ecclesiastical calendar
A church calendar of the Christian year, including the calculated dates of feasts and festivals.

Emperor John VIII
John Palaeologus, 1390-1448; ruler of the Byzantine Empire, 1425-1448. By the end of his reign, much of the Byzantine Empire had been conquered by the Ottoman Turks. His brother and successor, Constantine XI, would be the last Byzantine emperor.

The period in spring or winter when the sun crosses the equator and days and nights are of equal length.

first-order equation
An algebraic equation whose quantities are of the first power and an added constant (e.g., y = 3x + 4).

Now part of Belgium, during the Middle Ages a prosperous region that included parts of France, Belgium, and the Netherlands.

Toward the bow, or front, of a vessel.

To roll up a sail.

Upper timber of an individual frame or rib, joined to a lower timber attached to the keel.