1. (n.) An ultimate indivisible particle of matter.

2. (n.) An ultimate particle of matter not necessarily indivisible; a molecule.

3. (n.) A constituent particle of matter, or a molecule supposed to be made up of subordinate particles.

4. (n.) The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule.

5. (n.) Anything extremely small; a particle; a whit.

6. (v. t.) To reduce to atoms.