The Collaborative International Dictionary of English v.0.48:

Significance \Sig*nif"i*cance\, Significancy \Sig*nif"i*can*cy\,
   n. [L. significantia.]
   1. The quality or state of being significant.
      [1913 Webster]

   2. That which is signified; meaning; import; as, the
      significance of a nod, of a motion of the hand, or of a
      word or expression.
      [1913 Webster]

   3. Importance; moment; weight; consequence.
      [1913 Webster]

            With this brain I must work, in order to give
            significancy and value to the few facts which I
            possess.                              --De Quincey.
      [1913 Webster]

WordNet (r) 3.0 (2006):

significance
    n 1: the quality of being significant; "do not underestimate the
         significance of nuclear power" [ant: insignificance]
    2: a meaning that is not expressly stated but can be inferred;
       "the significance of his remark became clear only later";
       "the expectation was spread both by word and by implication"
       [syn: significance, import, implication]
    3: the message that is intended or expressed or signified; "what
       is the meaning of this sentence"; "the significance of a red
       traffic light"; "the signification of Chinese characters";
       "the import of his announcement was ambiguous" [syn:
       meaning, significance, signification, import]

Moby Thesaurus II by Grady Ward, 1.0:

135 Moby Thesaurus words for "significance":
   accent, acceptation, affective meaning, authority, balefulness,
   banefulness, bearing, bodefulness, coloring, concern, concernment,
   connotation, consequence, consequentiality, consideration,
   conspicuousness, content, credit, denotation, direness,
   distinction, doomfulness, drift, effect, elevation, eminence,
   emphasis, essence, exaltation, excellence, expressiveness,
   extension, fatality, fatefulness, force, gist, grammatical meaning,
   grandeur, greatness, high mightiness, high order, high rank, idea,
   impact, implication, import, importance, impression, influence,
   intelligibility, intendment, intension, interest, interpretability,
   lexical meaning, literal meaning, loftiness, magnitude, mark,
   materiality, meaning, meaningfulness, meatiness, merit, message,
   moment, momentousness, nobility, notability, note, ominousness,
   outstandingness, overtone, paramountcy, perfection, pertinence,
   pith, pithiness, point, portent, portentousness,
   practical consequence, precedence, preeminence, pregnancy,
   presagefulness, prestige, primacy, priority, prominence, purport,
   range of meaning, readability, real meaning, reference, referent,
   relation, relevance, scope, self-importance, semantic cluster,
   semantic field, sense, sententiousness, significancy,
   significantness, signification, significatum, signifie,
   sinisterness, span of meaning, spirit, stress, structural meaning,
   sublimity, substance, suggestiveness, sum, sum and substance,
   supereminence, superiority, supremacy, symbolic meaning, tenor,
   totality of associations, transferred meaning, unadorned meaning,
   understanding, undertone, value, vein, virtue, weight, weightiness,
   worth