noun

• A region in Southwest Asia spanning from the rivers Euphrates and Tigris that is the site of one of the most ancient civilizations in the history of man.
• (historical) The British Mandate of Mesopotamia, a League of Nations mandate from 1920 to 1932 that was the precursor to the independent state of Iraq.
• (UK, slang, obsolete) The Eaton Square district of London, England.