It's likely you're thinking of one of these related concepts:
1. Reflexive Pronoun:
* These pronouns refer back to the subject of the sentence. They are used when the subject of a verb performs an action on itself.
* Examples: *myself*, *yourself*, *himself*, *herself*, *itself*, *ourselves*, *yourselves*, *themselves*
* Example: *She dressed herself in a beautiful gown.*
2. Reflexive Verb:
* A verb that is used with a reflexive pronoun.
* Example: *He washed himself.*
3. Noun:
* A word that names a person, place, thing, or idea.
* Example: *The dog barked at the mailman.*
If you can provide more context or an example of what you mean by "reflex noun," I can help you understand the specific concept you are looking for.