What is the definition of a complete sentence as group words working together to do what?

A complete sentence is a group of words that work together to express a complete thought.

This means that the sentence must have:

* A subject: the person, place, or thing the sentence is about.

* A verb: the action the subject is performing or the state of being of the subject.

* A complete idea: The sentence conveys a meaningful thought that can stand alone.

Here's an example:

* The cat sat on the mat.

* Subject: The cat

* Verb: Sat

* Complete idea: The sentence expresses a complete thought about the cat's action.

Without one of these components, the sentence is considered incomplete or a fragment.