The Collaborative International Dictionary of English v.0.48:

Often \Of"ten\ ([o^]f"'n; 115), adv. [Compar. Oftener
   ([o^]f"'n*[~e]r); superl. Oftenest.] [Formerly also ofte,
   fr. oft. See Oft., adv.]
   Frequently; many times; not seldom.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Often \Of"ten\, a.
   Frequent; common; repeated. [R.] "Thine often infirmities."
   --1 Tim. v. 23.
   [1913 Webster]

         And weary thee with often welcomes.      --Beau. & Fl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

often
    adv 1: many times at short intervals; "we often met over a cup
           of coffee" [syn: frequently, often, oftentimes,
           oft, ofttimes] [ant: infrequently, rarely,
           seldom]
    2: frequently or in great quantities; "I don't drink much"; "I
       don't travel much" [syn: much, a great deal, often]
    3: in many cases or instances

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "often":
   again and again, commonly, continually, day after day, day by day,
   frequently, habitually, in many instances, many a time, many times,
   many times over, most often, much, not infrequently, not seldom,
   oft, often enough, oftentimes, ofttimes, ordinarily, over and over,
   recurrently, regularly, repeatedly, routinely, several times,
   time after time, time and again, times without number, unseldom,
   usually, whenever you wish, year after year