atom

1. (Physics) (a) An ultimate indivisible particle of matter. (b) An ultimate particle of matter not necessarily indivisible; a molecule. (c) A constituent particle of matter, or a molecule supposed to be made up of subordinate particles. Note: These three definitions correspond to different views of the nature of the ultimate particles of matter. In the case of the last two, the particles are more correctly called molecules. Dana. 2. (Chem.) The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule. 3. Anything extremely small; a particle; a whit. There was not an atom of water. Sir J. Ross. To reduce to atoms. [Obs.] Feltham.

Source: Webster's Revised Unabridged Dictionary (1913), United States public domain. See methodology for full licensing detail. Word validity for game play may differ from any official game dictionary.