What punctuation mark indicates a more definite break in the flow of sentence?

The punctuation mark that indicates a more definite break in the flow of a sentence is the period (.).

Here's why:

* Periods signal the end of a complete thought. They mark a full stop in the flow of ideas.

* Other punctuation marks, like commas (,) or semicolons (;), can also create pauses, but they do not signify the end of a complete sentence.

* Commas are used to separate items in a list, introduce clauses, or indicate a slight pause.

* Semicolons are used to connect closely related independent clauses.

So, while other punctuation marks create pauses, the period is the ultimate punctuation mark for a complete break in a sentence's flow.