The afterthought the car crash gave me was frightening.
something added, as a part or feature, that was not included in the original plan or design: The vestry was added to the church as an...
When it has a subject, verb, punctuation, capitalization, a predicate, and a complete thought. A sentence is a sentence when it is handed down by a judge (or a magistrate).
A sentence is a sentence because it has a subject (noun or noun phrase), a predicate ( verb) and punctuation as well as the other parts of speech like pronouns ( she, it him, her, they, them)...