Boyd’s Bible Dictionary:

(between rivers). The country between the rivers Tigris and Euphrates (Gen. 24:10; Deut. 23:4; {vi 6577-6579}Judg. 3:8-10; {vi 26959;27119}Acts 2:9; 7:2).

Concise Bible Dictionary:

This name signifies “midst of the rivers.” It is the district lying between the rivers Euphrates and the Upper Tigris, especially in the N.W. It is first mentioned as the abode of Nahor and his family. Isaac’s wife came from thence, and Jacob served Laban there. Mention is made of but one king of Mesopotamia, Chushan-rishathaim, who ruled over Israel—no doubt a part of them—for eight years ({vi 6577-6579}Judg. 3:8-10). Mesopotamia became absorbed in the great nations, belonging successively to the Assyrians, Medea and Persians, Greeks, and Romans; and is now possessed by the Turks (Gen. 24:10; Deut. 23:4; 1 Chron. 19:6; Acts 2:9; Acts 7:2). See ARAM-NAHARAIM.

Jackson’s Dictionary of Scripture Proper Names: