Final answer:
The term 'atom', meaning 'indivisible', was introduced by Greek philosophers Leucippus and Democritus in the fifth century BC, describing the smallest particles of matter that make up the physical world.
Step-by-step explanation:
The term atom, meaning 'indivisible', was first coined by the ancient Greek philosophers Leucippus and Democritus in the fifth century BC. They introduced the idea that the physical world was made up of small, indivisible particles called atoms, along with the void in which they exist and move.
Democritus, in particular, believed atoms couldn't be broken into smaller pieces and named them atomos, from the Greek ἀτομον which translates to 'uncuttable' or 'indivisible'. Furthermore, they theorized that these atoms moved in constant motion and interacted with one another, forming the diversity of objects seen in the physical world.