A noun names something — a person, place, thing or idea. A verb expresses an action or a state of being. The complication in English is that a great many words are both: "run" is a verb in "I run" and a noun in "a run". Position in the sentence, not the word itself, usually decides.
The core difference
The two most basic parts of speech, and the ones that overlap most in English.
- noun — names: dog, London, freedom, a run.
- verb — acts or states: run, seem, is.
How to tell which one you are looking at
Test the slot, not the word. If it follows the or a, or can be made plural, it is behaving as a noun. If it changes for tense — ran, running — it is behaving as a verb. "I run" and "a run" contain the same letters doing entirely different jobs.
Conversion
English turns nouns into verbs freely: to google, to text, to host. This is called conversion or zero-derivation, and it is one of the language's most productive habits — which is why the noun/verb boundary is fluid rather than fixed.
