The Collaborative International Dictionary of English v.0.48:

Augustan \Au*gus"tan\, a. [L. Augustanus, fr. Augustus. See
   August, n.]
   1. Of or pertaining to Augustus C[ae]sar or to his times.
      [1913 Webster]

   2. Of or pertaining to the town of Augsburg.
      [1913 Webster]

   Augustan age of any national literature, the period of its
      highest state of purity and refinement; -- so called
      because the reign of Augustus C[ae]sar was the golden age
      of Roman literature. Thus the reign of Louis XIV. (b.
      1638) has been called the Augustan age of French
      literature, and that of Queen Anne (b. 1664) the Augustan
      age of English literature.

   Augustan confession (Eccl. Hist.), or confession of
      Augsburg, drawn up at Augusta Vindelicorum, or Augsburg,
      by Luther and Melanchthon, in 1530, contains the
      principles of the Protestants, and their reasons for
      separating from the Roman Catholic church.
      [1913 Webster] Augustine