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The term Muslim world, also known as Islamic world and the Ummah (Arabic: أمة‎, meaning "nation" or "community") has different meanings. In a religious sense, the Islamic Ummah refers to those who adhere to the teachings of Islam, referred to as Muslims. In a cultural sense, the Muslim Ummah refers to Islamic civilization, exclusive of non-Muslims living in that civilization. In a modern geopolitical sense, the term "Islamic Nation" usually refers collectively to Muslim-majority countries, states, districts, or towns.

Islamic World is another way to refer to what?
Muslim world