Lewis & Short

† ătŏmus, a, um, adj., = ἄτομος.

  1. I. Uncut, not to be cut, indivisible: Graeci (tus) stagonian et atomum tali modo appellant, Plin. 12, 14, 32, § 62.
    Far more freq.,
  2. II. Subst.: ătŏmus (-ŏs), i, f., = ἡ ἄτομος, an indivisible element.
    1. A. Of matter, an atom, of which particles, acc. to the doctrine of Democritus, all things are composed (the distinction between an atom, an ultimate particle of matter, and a molecule, the ultimate combination of matter, was of course unknown to the ancients; syn.: corpora, corpora parva, corpora minuta, corpuscula, Lucr., Cic.): atomi, id est corpora individua propter soliditatem, Cic. Fin. 1, 6, 17; id. Tusc. 1, 18, 42; id. N. D. 1, 20, 54; id. Fat. 11, 24; id. N. D. 1, 24, 66; id. Ac. 1, 2, 6 al.; Vitr. 2, 2; Lact. de Ira Dei, 10 (where, as in Vitr. 2, 2, acc. to several editt., it stands as masc.); Isid. Orig. 13, 2, 1 sqq.
    2. B. Of time: in atomo, after the Gr. ἐν ἀτόμῳ, in a moment, in the twinkling of an eye, Tert. Res. Carn. 42 and 51; id. adv. Marc. 3, 24; so in the Gr. Test. 1 Cor. 15, 52, but rendered in momento by the Vulg.