What is Honesty?

Legal Definition
Honesty refers to a facet of moral character and connotes positive and virtuous attributes such as integrity, truthfulness, straightforwardness, including straightforwardness of conduct, along with the absence of lying, cheating, theft, etc. Furthermore, honesty means being trustworthy, loyal, fair, and sincere.

Honesty is valued in many ethnic and religious cultures. "Honesty is the best policy" is a proverb of Benjamin Franklin; however, the quote "Honesty is the first chapter in the book of wisdom" is attributed to Thomas Jefferson, as used in a letter to Nathaniel Macon.

Others have noted, however, that "[t]oo much honesty might be seen as undisciplined openness". For example, individuals may be perceived as being "too honest" if they honestly express negative opinions of others, either without having been asked their opinion, or having been asked in a circumstance where the response would be trivial.
-- Wikipedia
Legal Definition
That principle which requires us to give every one his due. Nul ne doit slenrichir aux de ens du droit d'autrui.

2. The very object of social order is to promote honesty, and to restrain dishonesty; to do justice and to prevent injustice. It is no less a maxim of law than of religion, do unto others as you wish to be done by.
-- Bouviers Law Dictionary