Tanna (tannaim, plural) was a Jewish sage during the first and second centuries. Notably they were teachers who handed down the oral law and midrashim, and were distinguished in the Talmud from the amoriam. During the period of the tannaim the Hebrews suffered two major defeats: the destruction of Jerusalem in 70 AD, and the failure of the Bar Kokhba revolt in 135. Despite the disasters, the tannaim succeeded in maintaining the authority of the Great Sanhedrin, establishing the yeshivot, and finally codifying the oral tradition in the Mishna. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 948