Atom – ORIGIN late 15th cent.: from Old French atome, via Latin from Greek atomos ‘indivisible,’ based on a– ‘not’ + temnein ‘to cut.’

Individual – ORIGIN late Middle English (in the sense of indivisible): from medieval Latin individualis, from Latin individuus, from in– ‘not’ + dividuus ‘divisible’ (from dividere ‘to divide’ ).