Nobility was/is still in some countries a social class which possesses more acknowledged privileges or eminenece than members of most other classes in a society, membership therein typically being...
They are the titles bestowed by a monarch and expressly forbidden by the US constitution. Although there are US citizens who covertly hold honorary British and European knighthoods etc.
No one, the founding fathers outlawed the ability to give anyone title of nobility, because they wanted the people to have the power, not just one person. (president isn't a title of...