The Collaborative International Dictionary of English v.0.48:

Clarity \Clar"i*ty\, n. [L. claritas, fr. clarus clear: cf. F.
   clart['e].]
   Clearness; brightness; splendor.
   [1913 Webster]

         Floods, in whose more than crystal clarity,
         Innumerable virgin graces row.           --Beaumont.
   [1913 Webster]

WordNet (r) 3.0 (2006):

clarity
    n 1: free from obscurity and easy to understand; the
         comprehensibility of clear expression [syn: clarity,
         lucidity, lucidness, pellucidity, clearness,
         limpidity] [ant: abstruseness, obscureness,
         obscurity, reconditeness, unclearness]
    2: the quality of clear water; "when she awoke the clarity was
       back in her eyes" [syn: clearness, clarity,
       uncloudedness] [ant: opacity, opaqueness]

Moby Thesaurus II by Grady Ward, 1.0:

134 Moby Thesaurus words for "clarity":
   Atticism, accuracy, admission of light, appropriateness,
   articulateness, articulation, atmospheric visibility, care,
   ceiling, ceiling unlimited, chasteness, chastity, classicalism,
   classicism, clear coast, clear road, clear-cutness, clearness,
   coherence, comeliness, comprehensibility, connectedness,
   consistency, conspicuity, conspicuousness, correctitude,
   correctness, crystal-clearness, crystallinity, definiteness,
   definition, diaphaneity, diaphanousness, dignity, directness,
   discrimination, distinction, distinctness, ease, easiness,
   easy going, effortlessness, elegance, elegancy, evidence,
   evidentness, exactitude, explicitness, facileness, facility,
   felicitousness, felicity, filminess, finish, fittingness, flow,
   flowing periods, fluency, freedom, fussiness, gauziness,
   glassiness, glasslikeness, good taste, gossameriness, grace,
   gracefulness, gracility, high visibility, highroad,
   intelligibility, lack of hindrance, limpidity, low visibility,
   lucidity, manifestness, meticulousness, naturalness, neatness,
   nicety, nonopacity, obviousness, patentness, pellucidity, percipi,
   perspicuity, plain English, plain sailing, plain speech,
   plain style, plainness, plane sailing, polish, precision,
   prominence, propriety, purity, refinement, restraint, royal road,
   seeing, seemliness, sheerness, show-through, simplicity,
   smooth road, smooth sailing, smoothness, straight sailing,
   straightforwardness, structure, taste, tastefulness, terseness,
   thinness, transmission of light, transparence, transparency,
   transpicuity, transpicuousness, unadorned style, unaffectedness,
   unambiguousness, uncloudedness, uncomplexity, uncomplicatedness,
   understandability, unequivocalness, unmistakableness,
   visibility unlimited, visibility zero, vitreosity, vitreousness,
   vitrescence