atom Copy link Outline I. An ultimate particle1. ătŏmus, i, f.2. corpus indīvĭduum, Cic.3. corpus insĕcābĭle4. (In pl. of the Epicurean atoms)II. A very small quantity • atom: I. An ultimate particle: 1. ătŏmus, i, f.: Cic. 2. corpus indīvĭduum, Cic.: Vitr. 3. corpus insĕcābĭle: Vitr.: Quint. 4. (In pl. of the Epicurean atoms): semina rerum, primordia: Lucr. 1, 502; also figurae, ib. 3, 191, etc. II. A very small quantity: mĭca, partĭcŭla: v. grain, morsel. Phr.: not an a., ne tantulum (tantillum) quidem, Cic.