The Collaborative International Dictionary of English v.0.48:

Corollary \Cor"ol*la*ry\ (k?r"?l-l?-r?; 277), n.; pl.
   Corollaries (-r?z). [L. corollarium gift, corollary, fr.
   corolla. See Corolla.]
   1. That which is given beyond what is actually due, as a
      garland of flowers in addition to wages; surplus;
      something added or superfluous. [Obs.]
      [1913 Webster]

            Now come, my Ariel; bring a corollary,
            Rather than want a spirit.            --Shak.
      [1913 Webster]

   2. Something which follows from the demonstration of a
      proposition; an additional inference or deduction from a
      demonstrated proposition; a consequence.
      [1913 Webster] Corollate

WordNet (r) 3.0 (2006):

corollary
    n 1: a practical consequence that follows naturally; "blind
         jealousy is a frequent corollary of passionate love"
    2: (logic) an inference that follows directly from the proof of
       another proposition

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "corollary":
   accession, accessory, accompaniment, addenda, addendum, additament,
   addition, additive, additory, additum, adjunct, adjuvant,
   aftereffect, annex, annexation, appanage, appendage, appendant,
   appurtenance, appurtenant, attachment, attendant, augment,
   augmentation, by-product, coda, complement, conclusion,
   concomitant, consequence, consequent, continuation, deduction,
   derivation, derivative, development, distillate, effect,
   end product, event, eventuality, eventuation, extension,
   extrapolation, fixture, fruit, harvest, illation, increase,
   increment, induction, inference, issue, legacy, logical outcome,
   offshoot, offspring, outcome, outgrowth, pendant, precipitate,
   product, reinforcement, result, resultant, sequel, sequela,
   sequence, sequent, side effect, side issue, supplement, tailpiece,
   undergirding, upshot