The Collaborative International Dictionary of English v.0.48:

Ripen \Rip"en\, v. i. [imp. & p. p. Ripened;p. pr. & vb. n.
   Ripening.]
   1. To grow ripe; to become mature, as grain, fruit, flowers,
      and the like; as, grapes ripen in the sun.
      [1913 Webster]

   2. To approach or come to perfection.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ripen \Rip"en\, v. t.
   1. To cause to mature; to make ripe; as, the warm days
      ripened the corn.
      [1913 Webster]

   2. To mature; to fit or prepare; to bring to perfection; as,
      to ripen the judgment.
      [1913 Webster]

            When faith and love, which parted from thee never,
            Had ripined thy iust soul to dwell with God.
                                                  --Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ripen
    v 1: cause to ripen or develop fully; "The sun ripens the
         fruit"; "Age matures a good wine" [syn: ripen, mature]
    2: grow ripe; "The plums ripen in July"

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "ripen":
   advance, age, alter into, attain majority, be converted into,
   bear fruit, beautify, become, better, bloom, blossom, blow,
   bring to maturity, change into, come of age, come round to,
   come to fruition, come to maturity, complete, crown, culminate,
   cultivate, develop, do to perfection, elaborate, embellish,
   enhance, evolute, evolve, evolve into, fall into, fester, finish,
   fledge, flourish, flower, grow, grow up, heighten, improve,
   intensify, lapse into, leave the nest, matter, maturate, mature,
   mellow, melt into, open into, pass into, perfect, polish, progress,
   rankle, reach its season, reach manhood, reach maturity,
   reach twenty-one, reach voting age, refine, ripe, ripen into, run,
   run into, season, settle down, settle into, shift into, suppurate,
   temper, toga virilis, turn into, turn to, wax, weep