2. (noun)Islam, Islamism, Mohammedanism, Muhammadanism, Muslimism the monotheistic religioussystem of Muslims founded in Arabia in the 7th century and based on the teachings of Muhammad as laid down in the Koran "Islam is a complete way of life, not a Sunday religion"; "the term Muhammadanism is offensive to Muslims who believe that Allah, not Muhammad, founded their religion"