Sunna Syllabification: (Sun·na)Pronunciation: /ˈsənə/Definition of Sunna noun the traditional portion of Muslim law based on Muhammad’s words or acts, accepted (together with the Koran) as authoritative by Muslims and followed particularly by Sunni Muslims. Origin:Arabic, literally 'form, way, course, rule'Sunna in other Oxford dictionaries Definition of Sunna in the British & World English dictionary