[1] : The Collaborative International Dictionary of English v.0.48

readable \read"able\ r=ed".ab'l, a.
   such as can be read; legible; fit or suitable to be read;
   worth reading; interesting. -- read"ableness, n. --
   read"ably, adv.
   1913 webster
see also:
read"ableness read"ably 

[2] : WordNet (r) 2.0

readable
     adj : easily deciphered syn: clear, decipherable
see also:
clear decipherable 

[3] : Moby Thesaurus II by Grady Ward, 1.0

80 moby thesaurus words for "readable":
   absorbing, allegorical, apprehensible, articulate, associational,
   cognizable, comprehensible, connotational, connotative,
   decipherable, definable, denotational, denotative, distinct,
   easily understood, easy to understand, engaging, enjoyable,
   entertaining, exciting, exoteric, expressive, extended,
   extensional, fair, fathomable, figurative, full of meaning,
   full of point, full of substance, in the clear, indicative,
   intelligible, intensional, interesting, interpretable, inviting,
   juicy, knowable, legible, lively, meaning, meaningful, meaty,
   metaphorical, penetrable, piquant, pithy, plain, pleasurable,
   plumbable, pointed, pregnant, prehensible, provocative, provoking,
   racy, referential, rich, scrutable, sententious, significant,
   significative, spicy, stimulating, substantial, succulent,
   suggestive, symbolic, tantalizing, thought-challenging,
   thought-inspiring, thought-provoking, tickling, titillating,
   transferred, uncoded, understandable, unenciphered, worthwhile

Readable >> R Words
Readable, definition of term: Readable
readable_pag1.html