dodecade

plural dodecades

1. alternativeAlternative form of duodecade (“period of twelve years”).
2. alternativeAlternative form of dodecad (“group of twelve”).

   [...] review of the events and changes that occurred during the dodecade. There was a crisis both in the affairs of the Colonies and in the affairs of the Mother Country, [...]

   1898, William Fishbough, The End of the Ages: With Forecasts of the Approaching Political, Social and Religious Reconstruction of America and the World, page 31

   1 more example

   The reader can call them to memory, to complete the scene with which the dodecade of famous years began. In 1859 Napoleon flung himself into the contest between the Italian kingdom of Sardinia and the Austrian power.

   1900, The International, page 218