The name among the Dúnedain for the ninth month of the year, more commonly known in Middle-earth by its Quenya title, Yavannië, and approximately equivalent to modern September. Its name comes from the words yávë 'fruit' and anna 'gift', a reference to the harvests of autumn, and connected to the name of Yavanna, the Vala of earth and growth.

The month of Ivanneth in the second year of the Third Age is historically important as the time when Isildur set out from Osgiliath to ride for the North-kingdom of the Dúnedain. Before the month was out, he and his companions were set upon by Orcs out of the autumn-coloured trees of Mirkwood, and the Ring Isildur bore was lost in the Great River.