The plain of Aram, or the plain of the highlands, (Genesis 25:20; 28:2,5-7; 31:18, etc.), commonly regarded as the district of Mesopotamia (q.v.) lying around Haran.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Padan-aram'". "Easton's Bible Dictionary".