微塵
みじん · mijin · JLPT N1 · noun
atom
🌫️ Sounds like 'me-jin', a tiny dust mote: the old word for the smallest bit, close to 'atom'.
微 (mi, tiny) + 塵 (jin, dust). In Japanese, 微塵 means a speck of dust, and it gives the sense of something ground down until nothing bigger is left, so 'atom' fits.