Atomism/ˈætəmɪzəm/ Definition 1 of 3Pro Tip 1/3Physical Reality Atomism often refers to physical objects being built from small units. He explained atomism by comparing it to a LEGO model. Pro Tip 2/3Ancient Roots Atomism has a long history, originally proposed by ancient philosophers. Democritus was an early advocate for atomism. Pro Tip 3/3Not Always Literal Atomism can be metaphorical, not just about literal atoms. He used atomism to discuss ideas, not just matter.