atom
/ˈætəm/
noun
- The smallest unit of a chemical element, made up of a nucleus and electrons.
- The model of the atom has changed a lot since ancient times.
- Scientists have split the atom to release enormous energy.
- A water molecule is made of two hydrogen atoms and one oxygen atom.
- A very small amount or particle of something.
- She didn't have an atom of doubt about her decision.
- There isn't an atom of truth in that rumor.
- He felt not an atom of guilt for telling the truth.