caliph
The supreme religious and political authority of Muslims, considered successor of Muhammad (Arabic: khalifa = deputy). He was the head of the Caliphate, the religious state of the Arabs.

Greek fire
Incendiary mixture based on crude oil (‘naphtha’), which was launched with the help of a pressure pump. Its used was spread in Byzantium towards the late 7th century and became one of the most powerful weapons of the Byzantine navy until the invention of canons.

litra (lat. libra)
A unit of weigth varying according to size. The most common was the "logarike litra", established at the time of cosntantine I in 309-310 as the basis of the monetary system. It was estimated as weighing ca. 324 or 319 g and was divides into 72 golden coins (solidi). One hundred litrai made a kentenarion.

patrikios
(from lat. patricius) Higher title of honour, placed, according to the "Tactika" of the 9th and the 10th centuries, between anthypatos and protospatharios. It was given to the most important governors and generals. Gradually, however, it fell into disuse and from the 12th century did not exist any more.