The Collaborative International Dictionary of English v.0.48:

Consistence \Con*sist"ence\, Consistency \Con*sist"en*cy\, n.
   [Cf. F. consistance.]
   1. The condition of standing or adhering together, or being
      fixed in union, as the parts of a body; existence;
      firmness; coherence; solidity.
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            Water, being divided, maketh many circles, till it
            restore itself to the natural consistence. --Bacon.
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            We are as water, weak, and of no consistence. --Jer.
                                                  Taylor.
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            The same form, substance, and consistency. --T.
                                                  Burnet.
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   2. A degree of firmness, density, viscosity, or spissitude; a
      measure of the ability to hold together when manipulated.

   Syn: body.
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              Let the expressed juices be boiled into the
              consistence of a sirup.             --Arbuthnot.
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   3. That which stands together as a united whole; a
      combination.
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            The church of God, as meaning the whole consistence
            of orders and members.                --Milton.
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   4. Firmness of constitution or character; substantiality;
      durability; persistency.
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            His friendship is of a noble make and a lasting
            consistency.                          --South.
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   5. Agreement or harmony of all parts of a complex thing among
      themselves, or of the same thing with itself at different
      times; the harmony of conduct with profession; congruity;
      correspondence; as, the consistency of laws, regulations,
      or judicial decisions; consistency of opinions;
      consistency of conduct or of character.
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            That consistency of behavior whereby he inflexibly
            pursues those measures which appear the most just.
                                                  --Addison.
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            Consistency, thou art a jewel.        --Popular
                                                  Saying.
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WordNet (r) 3.0 (2006):

consistency
    n 1: the property of holding together and retaining its shape;
         "wool has more body than rayon"; "when the dough has enough
         consistency it is ready to bake" [syn: consistency,
         consistence, eubstance, body]
    2: a harmonious uniformity or agreement among things or parts
       [syn: consistency, consistence] [ant: inconsistency]
    3: logical coherence and accordance with the facts; "a rambling
       argument that lacked any consistency"
    4: (logic) an attribute of a logical system that is so
       constituted that none of the propositions deducible from the
       axioms contradict one another

Moby Thesaurus II by Grady Ward, 1.0:

170 Moby Thesaurus words for "consistency":
   accommodation, accord, accordance, acquiescence, adaptation,
   adaption, adhesiveness, adjustment, affinity, agreement,
   apposition, aptness, assent, balance, bilateral symmetry,
   bullheadedness, calm, chorus, clarity, clear-cutness, clearness,
   closeness, coherence, cohesiveness, coincidence, compactness,
   compatibility, compliance, concert, concord, concordance,
   conformance, conformation, conformation other-direction,
   conformity, congeniality, congestedness, congestion, congruence,
   congruency, congruity, connectedness, connection, consecutiveness,
   consistence, consonance, consort, constancy, continuity,
   conventionality, cooperation, correspondence, crowdedness,
   crystallinity, definition, denseness, density, directness,
   distinctness, dynamic symmetry, equability, equality, equanimity,
   equilibrium, equivalence, eurythmics, eurythmy, evenness,
   explicitness, felicity, finish, firmness, fitness, flexibility,
   gluiness, glutinosity, gumminess, hardness, harmony, homogeneity,
   impenetrability, impermeability, imporosity, incompressibility,
   intersection, jammedness, keeping, likeness, limpidity, line,
   lucidity, malleability, monolithism, multilateral symmetry,
   obedience, observance, obstinacy, oneness, orderliness, orthodoxy,
   overlap, parallelism, peace, pellucidity, persistence, persistency,
   perspicuity, plain English, plain speech, plain style, plainness,
   pliancy, polarity, proportion, proportionality, rapport,
   reconcilement, reconciliation, regularity, relative density,
   retention, self-consistency, sequence, shapeliness, similarity,
   simplicity, snugness, solidity, solidness, specific gravity,
   spissitude, stability, steadfastness, steadiness,
   stick-to-itiveness, stickiness, straightforwardness, strictness,
   structure, stubbornness, suitability, symmetricalness, symmetry,
   sync, synchronism, tackiness, tally, tenaciousness, tenacity,
   thickness, tightness, timing, toughness, traditionalism,
   transparency, transpicuity, trilateral symmetry, unadorned style,
   unambiguousness, unequivocalness, uniformity, union, unison,
   unisonance, unity, unmistakableness, unruffledness, viscidity,
   viscosity, viscousness