Source : Webster's Revised Unabridged Dictionary (1913)

Olden \Old"en\, v. i.
   To grow old; to age. [R.]

         She had oldened in that time.            --Thackeray.

Olden \Old"en\, a.
   Old; ancient; as, the olden time. ``A minstrel of the olden
   stamp.'' --J. C. Shairp.

Source : WordNet®

olden
     adj : of time long past; "olden days"