What is a group of words missing subject verb or complete thought called?

A group of words missing a subject, verb, or a complete thought is called a phrase.

Here's why:

* Subject: A phrase doesn't have a noun or pronoun performing an action.

* Verb: A phrase lacks the action or state of being.

* Complete thought: A phrase doesn't express a complete idea.

For example:

* "Running through the park" (phrase) - No subject (who is running?) or verb (what is being done?).

* "Under the bright, blue sky" (phrase) - No subject or verb.

Note: A clause contains a subject and a verb, but it may not have a complete thought.