You searched for: “mononymy
mononymy
A term which refers to anyone who uses only one name; such as, Madonna, Pelé, Odetta, Cher, Voltaire, Aristotle, Cicero, Adam, Eve (Adam and Eve), Hannibal, Hippocrates, Houdini, Michelangelo, Pythagoras, Socrates, Spartacus, and many others.

Uninomial also has the same application.