The Collaborative International Dictionary of English v.0.48:

Honorable \Hon"or*a*ble\ ([o^]n"[~e]r*[.a]*b'l), a. [F.
   honorable, L. honorabilis.]
   1. Worthy of honor; fit to be esteemed or regarded;
      estimable; illustrious.
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            Thy name and honorable family.        --Shak.
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   2. High-minded; actuated by principles of honor, or a
      scrupulous regard to probity, rectitude, or reputation.
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   3. Proceeding from an upright and laudable cause, or directed
      to a just and proper end; not base; irreproachable; fair;
      as, an honorable motive.
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            Is this proceeding just and honorable? --Shak.
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   4. Conferring honor, or produced by noble deeds.
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            Honorable wounds from battle brought. --Dryden.
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   5. Worthy of respect; regarded with esteem; to be commended;
      consistent with honor or rectitude.
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            Marriage is honorable in all.         --Heb. xiii.
                                                  4.
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   6. Performed or accompanied with marks of honor, or with
      testimonies of esteem; as, an honorable burial.
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   7. Of reputable association or use; respectable.
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            Let her descend: my chambers are honorable. --Shak.
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   8. An epithet of respect or distinction; as, the honorable
      Senate; the honorable gentleman.
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   Note: Honorable is a title of quality, conferred by English
         usage upon the younger children of earls and all the
         children of viscounts and barons. The maids of honor,
         lords of session, and the supreme judges of England and
         Ireland are entitled to the prefix. In American usage,
         it is a title of courtesy merely, bestowed upon those
         who hold, or have held, any of the higher public
         offices, esp. governors, judges, members of Congress or
         of the Senate, mayors, and often also extended to lower
         officials, such as city council members.
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   Right honorable. See under Right.
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WordNet (r) 3.0 (2006):

honorable
    adj 1: not disposed to cheat or defraud; not deceptive or
           fraudulent; "honest lawyers"; "honest reporting" [syn:
           honest, honorable] [ant: dishonest, dishonorable]
    2: worthy of being honored; entitled to honor and respect; "an
       honorable man"; "led an honorable life"; "honorable service
       to his country" [syn: honorable, honourable] [ant:
       dishonorable, dishonourable]
    3: adhering to ethical and moral principles; "it seems ethical
       and right"; "followed the only honorable course of action"
       [syn: ethical, honorable, honourable]
    4: deserving of esteem and respect; "all respectable companies
       give guarantees"; "ruined the family's good name" [syn:
       estimable, good, honorable, respectable]

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "honorable":
   Christian, acclaimed, appropriate, artless, august, awe-inspiring,
   awesome, awful, blameless, celebrated, clean, conscientious,
   correct, creditable, decent, disinterested, distinguished,
   dreadful, eminent, equitable, erect, esteemed, estimable, ethical,
   exalted, fair, fair and square, famed, famous, fitting,
   full of integrity, good, guileless, held in esteem, high-minded,
   high-principled, highly esteemed, highly regarded, highly reputed,
   highly respectable, honest, honorary, honored, honorific,
   illustrious, immaculate, impartial, in favor, in good odor,
   in high favor, incorruptible, ingenuous, inviolate, irreproachable,
   just, law-abiding, law-loving, law-revering, manly, meritorious,
   moral, noble, notable, noted, noteworthy, on the level, open,
   prestigious, principled, proper, pure, renowned, reputable,
   respectable, respected, revered, reverend, right, right-minded,
   righteous, scrupulous, sincere, spotless, square, stainless,
   sterling, straight, time-honored, true, true-dealing, true-devoted,
   true-disposing, true-souled, true-spirited, truehearted,
   trustworthy, trusty, unbiased, unblemished, uncorrupt, uncorrupted,
   undeceitful, undeceiving, undefiled, unimpeachable, unprejudiced,
   unspotted, unstained, unsullied, untarnished, upright, uprighteous,
   upstanding, venerable, venerated, virtuous, well-thought-of,
   worshipful, worthy, yeomanly



The Devil's Dictionary (1881-1906):

HONORABLE, adj.  Afflicted with an impediment in one's reach.  In
legislative bodies it is customary to mention all members as
honorable; as, "the honorable gentleman is a scurvy cur."