kommerkion
This name had two meanings in Byzantium 1. Commercium (lat.), which in late Roman times designated the frontier cities where exchanges with foreign merchants were authorised. 2. Kommerkion, which was a circulation and sales tax, paid at the customs, and collected on mercandise imported into the empire and on merchandise reaching Constantinople by the sea. It appears in the sources c. 800 and was also called dekate, its rate being 10 percent of the merchandise value.

province
An administrative unit in the Roman and Byzantine Empire. Established in the Roman Empire it is radically reformed by Diocletian, who abolishes the distinction between imperial and senatorial provinces and increases their number by dividing large provinces into smaller ones. Moreover, Diocletian divided the State into 12 dioceses, which included groups of provinces. Administrative reformations in the Byzantine era further increased the number of provinces while reducing their size. Provinces survived until the emrgence of the administrative system of the themes, around 7th c. However the term appears on commerciarii seals until the 9th c., and in written sources of the 11th-12th c. as a synonym of the theme.

strategos ("general")
During the Roman period his duties were mainly political. Οffice of the Byzantine state´s provincial administration. At first the title was given to the military and political administrator of the themes, namely of the big geographic and administrative unities of the Byzantine empire. Gradually the title lost its power and, already in the 11th century, strategoi were turned to simple commanders of military units, responsible for the defence of a region.

Synekdemos of Hierokles
A geographical text book composed a little before 535 by Hierokles the Grammarian. It constitutes a list of 64 provinces and 923 (originally 935) cities of the Empire, being the most important source for the administrative and political geography of the Byzantine Empire prior to the Arab raids. It is assumed to have been based on state documents, and presents the political, administrative, and, to an extent, the ecclesiastical geography from mid-5th c. However, it contains additions from the age of Justinian I, while some of its evidence is still under discussion. Constantine VII Porphyrogennetos used it as a major source, along with Stephen of Byzantium, for the composition of the work “De thematibus”. This most important work of Hierokles was published by G. Parthey (Hieroclis Synecdemus, Berlin, 1866), and A. Burckhardt (Hieroclis Synecdemus, Leipzig, 1893). The last and most authoritative edition is E. Honigmann (ed.), Le Synekdèmos d'Hiéroklès et l'opuscule géographique de Georges de Chypre (Brussels 1939).

theme
A Byzantine term that signifies wide military and administrative units under the administration of a strategos (general). The institution was consolidated in the 7th century and was characteristic for the organization and the division of Byzantine Empire at the Middle Byzantine period. The term applies also to the army unit that resided in each administrative unit and was staffed by farmer-soldiers. The thematic system was maintained until the end of Byzantine period. However, in the Later Byzantine period it was used in order to declare mostly tax units.

tourma
(lat. turma, meaning squadron) Administrative division of a theme in the Middle Byzantine period. A tourma was further subdivised into droungoi and banda.