Word Study
sunna
CIDE DICTIONARY
sunna, n. [Ar. sunnah rule, law.].
A collection of traditions received by the orthodox Mohammedans as of equal authority with the Koran. [1913 Webster]
OXFORD DICTIONARY
sunna, n. a traditional portion of Muslim law based on Muhammad's words or acts, accepted as authoritative by many Muslims but rejected by the Shiites.
Etymology
Arab., = form, way, course, rule
For further exploring for "sunna" in Webster Dictionary Online