| 1 | English | atom | The smallest possible amount of matter which... |
| 2 | Middle English | attome | atom |
| 3 | Middle French | athome | atom |
| 4 | Latin | atomus | indivisible; an atom, particle incapable of being... |
| 5 | Ancient Greek | ἄτομος | uncut; indivisible, not capable of being... |
| 6 | Ancient Greek | ἀ- | The alpha privativum, used to make words that... |
| 7 | Proto-Hellenic | hə- | same; together |
| 8 | Proto-Indo-European | sm̥- | one; with, together |
| 9 | Proto-Indo-European | sem- | together, one |