What is the Latin word for atom?

The usual Latin words for “atom” are atomus, fīlius. The right choice depends on the sense; see the distinctions below.

English → Latin

“atom” in Latin

atomusindivisible fīliusa son; any male descendant; children

The English word atom itself goes back to Latin atomus.

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

atom

atomus, i, f. (ἡ ἀτομος): corpus individuum (Cic.): corpus individuum et solidum (Cic.): corpus insecabile (Vitr., Quint.).

Used hyperbolically for a very small portion: not an atom, ne minimum quidem; ne tantillum quidem.

Quick answer

What is the Latin word for atom?: The usual Latin words for “atom” are atomus, fīlius. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.