Honorable, a.
Etymology: [F. honorable, L. honorabilis.]
1. Worthy of honor; fit to be esteemed or regarded; estimable; illustrious. Thy name and honorable family. Shak.
2. High-minded; actuated by principles of honor, or a scrupulous regard to probity, rectitude, or reputation.
3. Proceeding from an upright and laudable cause, or directed to a just and proper end; not base; irreproachable; fair; as, an honorable motive. Is this proceeding just and honorable Shak.
4. Conferring honor, or produced by noble deeds. Honorable wounds from battle brought. Dryden.
5 more senses
5. Worthy of respect; regarded with esteem; to be commended; consistent with honor or rectitude. Marriage is honorable in all. Heb. xiii. 4.
6. Performed or accompanied with marks of honor, or with testimonies of esteem; an honorable burial.
7. Of reputable association or use; respectable. Let her descend: my chambers are honorable. Shak.
8. An epithet of respect or distinction; as, the honorable Senate; the honorable gentleman.
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. Right honorable. See under Right.
Shades of meaning
Fernald has no entry of its own for honorable; he lists it under honest.
Where he writes about it:
One who is honest in the ordinary sense acts or is always disposed to act with careful regard for the rights of others, especially in matters of business or property; one who is honorable scrupulously observes the dictates of a personal honor that is higher than any demands of mercantile law or public opinion, and will do nothing unworthy of his own inherent nobility of soul. — from honest
The honest man does not steal, cheat, or defraud; the honorable man will not take an unfair advantage that would be allowed him, or will make a sacrifice which no one could require of him, when his own sense of right demands it. — from honest
In this sense honest differs from honorable as having regard rather to absolute truth and right than to even the highest personal honor. — from honest