The Collaborative International Dictionary of English v.0.48:

Rife \Rife\, a. [AS. r[imac]f abundant, or Icel. r[imac]fr
   munificent; akin to OD. riff, rijve, abundant.]
   1. Prevailing; prevalent; abounding.
      [1913 Webster]

            Before the plague of London, inflammations of the
            lungs were rife and mortal.           --Arbuthnot.
      [1913 Webster]

            Even now the tumult of loud mirth
            Was rife, and perfect in may listening ear.
                                                  --Milton.
      [1913 Webster]

   2. Having power; active; nimble. [Obs.]
      [1913 Webster]

            What! I am rife a little yet.         --J. Webster.
      [1913 Webster] -- Rife"ly, adv. -- Rife"ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rife
    adj 1: most frequent or common; "prevailing winds" [syn:
           prevailing, prevalent, predominant, dominant,
           rife]
    2: excessively abundant [syn: overabundant, plethoric,
       rife]

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "rife":
   abounding, abundant, affluent, afloat, alive with, all-sufficing,
   ample, aplenty, average, bandied about, besetting, bottomless,
   bounteous, bountiful, bristling, bruited about, bursting, common,
   copious, crawling, crowded, crowding, current, diffuse, dominant,
   effuse, epidemic, exhaustless, extravagant, exuberant, fat,
   fertile, flush, full, galore, generous, going about, going around,
   in circulation, in plenty, in profusion, in quantity, in the air,
   in the news, inexhaustible, jam-packed, jammed, lavish, liberal,
   luxuriant, made public, many, maximal, much, normal, numerous,
   opulent, ordinary, overflowing, packed, pandemic, plenitudinous,
   plenteous, plentiful, plenty, popular, populous, predominant,
   predominating, prevailing, prevalent, prodigal, productive,
   profuse, profusive, proliferating, prolific, rampant, regnant,
   reigning, replete, reported, rich, riotous, routine, ruling,
   rumored, running, running over, standard, stereotyped, studded,
   superabundant, swarming, talked about, teeming, thick,
   thick as hail, thick with, thick-coming, thronged, thronging,
   usual, wealthy, well-found, well-furnished, well-provided,
   well-stocked, whispered, whispered about, wholesale, widespread