ancient name for the land that lies between the Tigris and Euphrates rivers north of Babylon (in modern Iraq), from Greek mesopotamia (khōra), literally "a country between two rivers," from fem. of mesopotamos, from mesos "middle" (from PIE root *medhyo- "middle") + potamos "river" (see potamo-).
In 19c. the word sometimes was used in the sense of "anything which gives irrational or inexplicable comfort to the hearer," based on the story of the old woman who told her pastor that she "found great support in that comfortable word Mesopotamia" ["Brewer's Dictionary of Phrase & Fable," 1870]. The place was Mespot (1917) to British soldiers serving there in World War I. Related: Mesopotamian.