honesty honor integrity probity rectitude

These nouns denote the quality of being upright in principle and action.

Honesty implies truthfulness, fairness in dealing with others, and refusal to engage in fraud, deceit, or dissembling:

Honesty is the best policy.

Honor implies principled uprightness of character and a worthy adherence to a strict moral or ethical code:

Never give in except to convictions of honor and good sense (Winston S. Churchill).

Integrity is moral soundness, especially as it is revealed in dealings that test steadfastness of purpose, responsibility, or trust:

Integrity without knowledge is weak and useless, and knowledge without integrity is dangerous and dreadful (Samuel Johnson).

Probity is proven integrity:

A judge must be a person of unquestioned probity.

Rectitude is moral righteousness both in principle and in practice:

The name of Brutus would be a guaranty to the people of rectitude of intention (J.A. Froude).