An ultimate indivisible particle of matter.
An ultimate particle of matter not necessarily indivisible; a molecule.
A constituent particle of matter, or a molecule supposed to be made up of subordinate particles.
The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule.
Anything extremely small; a particle; a whit. There was not an atom of water. Sir J. Ross.
To reduce to atoms. [Obs.] Feltham.
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