Final answer:
A'tomos in ancient Greece means indivisible, a concept from Democritus' theory that signified atoms as the smallest units of matter.
Step-by-step explanation:
The word A'tomos in ancient Greece means indivisible or uncuttable. This term originates from the Greek philosopher Democritus' atomic theory where he postulated that everything is composed of atoms, which are indivisible and indestructible units. While Democritus' theory was dismissed by other Greek philosophers and not fully appreciated until much later, it laid the groundwork for modern atomic theory in Chemistry and Physics.