Onomasticon (Eusebius)

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, Peri tōn topikōn onomatōn tōn en tē Theia Graphē, in Greek) is a directory of place names, or "gazetteer", a primary source that provides historical geographers with a contemporary knowledge of early 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 Palestine in the Roman period.