The same is related to a woman being a lady; a lady is a woman who is admirable, with a high level of appropriate and normal behavior. All females can be measured or called women, but not all women can be considered or called ladies as some may lack the characteristics that propel others to see them and call them a lady.
If a man is seen opening and holding a door for a lady to walk through, he is considered a gentleman. I remember my friend and I talking about her boyfriend, and she said he was a gentleman because he would hold the door open for her when they go out, and he is always the one carrying her handbag when they go out.
To her, these features shown by her boyfriend makes him a gentleman. A well-rounded person is a person that is fully developed, well balanced, and has varied abilities and attainment. There are various characteristics of a well-rounded person: A well-rounded person should be of a noble birth just like the definition of a gentleman.
The Courtier says “I wish them that this courtier of ours should be nobly born and of gentle race; . . . for noble birth is like a bright lamp that manifests and makes visible good and evil deeds. ( Sayre, The Perfect Courtier, para 4) A well-rounded person should have a likeable personality, and a true sense of self esteem. The Courtier says “I would have the courtier favored in this regard also, and endowed by nature not only with talent and beauty of person and feature, but with a certain grace and (as we say) air that make him at first sight pleasing and agreeable to all who see.