When I look to the source of all contemporary wisdom – wikipedia, it tells me:
Integrity is a concept of consistency of actions, values, methods, measures, principles, expectations, and outcomes. In ethics, integrity is regarded as the quality of having an intuitive sense of honesty and truthfulness in regard to the motivations for one’s actions. Integrity can be regarded as the opposite of hypocrisy, in that it regards internal consistency as a virtue, and suggests that parties holding apparently conflicting values should account for the discrepancy or alter their beliefs.
The word “integrity” stems from the Latin adjective integer (whole, complete). In this context, integrity is the inner sense of “wholeness” deriving from qualities such as honesty and consistency of character. As such, one may judge that others “have integrity” to the extent that one judges whether they behave according to the values, beliefs and principles they claim to hold.
I like this definition as it hones in on the concept of being complete. The complete Gentleman in one who acts consistently in line with their values with an intuitive sense of honesty. Love it!