The Collaborative International Dictionary of English v.0.48:

Recurrence \Re*cur"rence\ (r?*k?r"rens), Recurrency
\Re*cur"ren*cy\ (-ren*s?), n. [Cf. F. r['e]currence.]
   The act of recurring, or state of being recurrent; return;
   resort; recourse.
   [1913 Webster]

         I shall insensibly go on from a rare to a frequent
         recurrence to the dangerous preparations. --I. Taylor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

recurrence
    n 1: happening again (especially at regular intervals); "the
         return of spring" [syn: recurrence, return]

Moby Thesaurus II by Grady Ward, 1.0:

103 Moby Thesaurus words for "recurrence":
   Indian file, alternation, array, articulation, atavism, backset,
   backward deviation, bank, beat, buzz, catena, catenation, chain,
   chain reaction, chaining, concatenation, connection, consecution,
   continuum, course, cycle, cyclicalness, descent, doubling, drone,
   duplication, echo, endless belt, endless round, falling back, file,
   filiation, frequency, gamut, gradation, hum, imitation,
   intermittence, intermittency, lapse, line, lineage, meter,
   monotone, nexus, oscillation, pendulum, pendulum motion,
   periodicalness, periodicity, piston motion, plagiarism, plenum,
   powder train, progression, pulsation, queue, quotation, range,
   rank, reappearance, rebirth, recrudescence, redoubling,
   reduplication, reecho, regression, regular wave motion,
   regurgitation, reincarnation, relapse, renewal, reoccurrence,
   repetition, reproduction, resumption, reticulation, return,
   reversal, reverse, reversion, rhythm, rotation, round, routine,
   row, run, scale, seasonality, sequence, series, setback,
   single file, spectrum, string, succession, swath, thread,
   throwback, tier, train, undulation, windrow