What you mean by term quantum mechanics?
The term “quantum” came from the Latin word that implies "how great" or "how much" that is quantity. In quantum mechanics, that refers to a discrete unit which quantum theory assigns to exact physical quantities, as like the energy of an atom at rest. The innovation that waves have discrete energy packets (termed as quanta) which behave in a way similar to particles led to the branch of physics which deals along with atomic and subatomic systems that we today call quantum mechanics.