The Onomasticon compiled by Eusebius of Caesarea (more properly, On the Place-Names in the Holy Scripture, Περὶ τῶν τοπικῶν ὀνομάτων τῶν ἐν τῇ Θείᾳ Γραφῇ in greek) is a directory of place names, or "gazetteer", a primary source that provides historical geographers with a contemporary knowledge of 4th-century Palestine and Transjordan. It sits uneasily between the ancient genres of geography and lexicography, taking elements from both but serving as a member of neither. It is, according to many, the most important book for the study of the Land of Israel in the Roman period.
Eusebius' description of his own method, who wrote: "I shall collect the entries from the whole of the divinely inspired Scriptures, and I shall set them out grouped by their initial letters so that one may easily perceive what lies scattered throughout the text," implies that he had no similar type of book to work from; his work being entirely original, based only on the text of the Bible. Others have suggested that Eusebius had at his disposal early Roman maps of the Roman Empire with which to work, and which allowed him to record the precise distances between locations in Roman miles. Needless to say, this innovation has been very useful to modern research. Of the approximate 980 Biblical and New Testament names of places contained in those works, Eusebius identifies some 340 with locations known in his own day and age.
The primary source for the Onomasticon is Codex Vaticanus, Gr. 1456 which dates from the 11th or 12th century. Dependent upon this manuscript is Codex Parisinus Gr 464 which dates from the 16th century. These two manuscripts were edited and published by Lagarde in 1870.
Tina (Kinah, 15:22): of the tribe of Judah.
Telem (15:24): of the tribe of Judah.
Tessam ([Azem] 15:29): of the tribe of Judah.
Tyre ([Zer] 19:35): of the tribe of Naphthali.
Under each letter, the entries are organized first by the book they are found in, and then by their place in that book. In almost all of the entries in his geographical opus, Eusebius brings down the respective distances in Roman "milestones" (semeia) from major points of reference, such as from Jerusalem, Beit Gubrin (Eleutheropolis), Hebron, Ptolemais, Caesarea, etc. In Eusebius' Onomasticon, distances between each "milestone" were usually 1,600 meters–1,700 meters, although the standard Roman mile was 1,475 meters. Since most villages in the Onomasticon are far removed from Roman-built roads, scholars have concluded that Eusebius did not glean the geographical information from maps based on a milestone survey, but rather collected the information from some other source.
Where there is a contemporary town at the site or nearby, Eusebius notes it in the corresponding entry. "Terebinth", for example, describes Shechem as "near Neapolis", modern Nablus, and "Tophet" is located "in the suburbs of Jerusalem".
The Onomasticon has traditionally been dated before 324, on the basis of its sparse references to Christianity, and complete absence of remarks on Constantine the Great's buildings in the Holy Land. The work also describes traditional religious practices at the oak of Mamre as though they were still happening, while they are known to have been suppressed soon after 325, when a church was built on the site. Eusebius references to the encampment of the Legio X Fretensis at Aila (in southern Israel, near modern Aqaba and Eilat); the X Fretensis was probably transferred from Jerusalem to Aila under Diocletian.
- Barnes, Constantine and Eusebius, 106.
- R. Steven Notley and Ze'ev Safrai, Eusebius, Onomasticon - A Triglott Edition with Notes and Commentary, Introduction
- Onomasticon p. 2.14ff., qtd. and tr. Barnes, Constantine and Eusebius, 107.
- Barnes, Constantine and Eusebius, 106–7.
- Yoel Elitzur, Ancient Toponyms in Eretz-Israel as Preserved among the Arabs - The Linguistic Aspects, Hebrew University: Jerusalem 1992, Introduction
- Barnes, Constantine and Eusebius, 107.
- Benjamin Isaac and Israel Roll, Roman Roads in Judaea I – The Legio-Scythopolis Road, B.A.R. International Series, Oxford 1982, p. 12
- Barnes, "Onomasticon", 413.
- Barnes, "Onomasticon", 413 n. 4.