In physics, the scientific theory that matter is composed of atoms.
Atomic theory began in ancient Greece and was established in modern science.
atomism; atomic theory
In philosophy, the view that the universe consists of indivisible, minute particles.
Democritus's atomism argued that the world consists of atoms and void.
From 原子 (atom) + 論 (theory, discourse). The term is a straightforward compound used in both physics and philosophy.