The definition of gentleman is a man of refinement. Originally it was referring to men of wealth with no need to work hard labor, often able to live off the interest of their holdings.
It is said that Robert E. Lee was the last southern gentleman.
Does there exist “modern gentlemen” or “modern gentlewomen”? If so, who do you think is an example of one?
“He’s a real gentleman”
First and foremost this phrase says to me…wouldn’t take advantage of any kind of vulnerability in a woman to have sex with her that she might regret. So, not if she was drunk, or depressed, or just dumped, etc.
Of course it has the more general meaning of an all around good person, with the implication of rather more good than your average good person.
But when I usually hear it, it’s usually in the context of how a man treats women. Someone might say a man is a gentleman if he opens doors for women, or if he compliments them, but always always the implication is that the man treats women with respect and without sexual predation.
There are various definitions. One is “a gentleman is someone who can play the trombone…but doesn’t.”
Another that I recall from an old friend is “a gentleman never makes anyone feel uncomfortable…by accident.”
I’ve been called a gentleman, but never by unbiased sources. I do the simple things…opening doors…making sure the lady comes first and more often…but these are no more than should be expected.
Of course, I can use a sabre, shoot, ride…choose the wine, but so can many people.
In dealing with the general public, assuming that they wish me no ill, I treat them as if they were as noble as I. People seem to like that.
Winston Churchill said, “When you have to kill a man it costs nothing to be polite.”
In short, I try to live without disgusting myself. If you meet a man like that, that man is likely to be a gentleman.
To say that Robert E. Lee was the last southern gentleman is an insult to the South. There are millions of gentlemen and gentlewomen in the South, as there are in the rest of our country.
The meaning of gentleman has morphed since Robert E. Lee was around. You no longer have to be wealthy or landed. It is now an equal-opportunity category. It’s a way of behaving with kindness and politeness toward everyone. The rich can no longer say that the rest of us are not gentlemen. They can still say that the rest of us are not rich, of course, and that’s still a comfort to them. 
A gentleman is also always aware of his surroundings. Aware of the things that may cause trouble, or problems or difficulty. And a gentleman is always ready to offer help for those that may need it.
A true gentleman can make people feel valuable. I have met some people who can do this, and some who cannot. The royal family in general are known to be able to put people at their ease quickly and amusingly. I daresay it’s a skill they’ll all have needed since childhood - and I don’t doubt that they’re perfectly capable of making people feel utterly worthless, should the occasion arise. However it is something they’re known for. One would hardly be worthy of the title ‘gentleman’ if one felt one had to prove it by putting others down.
There’s no reason to confine the skill to nobility: anyone who can make someone feel like they’re a worthwhile human being, particularly when they didn’t feel that before, or when they and the gentleman are actually in some kind of conflict, is a gentleman. It shouldn’t be done by sitting people down and counselling them on their good points, either - nor by flattery. Just by the way you treat them.
A gentleman is polite, courteous, suave, well-mannered, elegant, and dignified. A gentlemen always holds doors and pulls out chairs and knows exactly what to say. A gentlemen wears only the finest suits and has the most expensive tastes. Like James Bond, minus all the shooting and spy work.
I want me a gentleman now.
A gentleman never leaves his Wife or any guest behind.
A gentleman knows that a smile is a better tool than a fist.
Winston Churchill said that a Gentleman never ‘causes harm unintentionally.’ This is a maxim I try to live up to. A Gentleman never uses force of any sort to get what he wants for himself, this includes social or financial pressure. He does use force, even violence to protect others. He treats others as he would wish to be treated.