What is the proper term for a run-on sentence that incorrectly punctuated with comma in middle of it instead semicolon or period?

The term for a run-on sentence incorrectly punctuated with a comma instead of a semicolon or period is comma splice.

Here's why:

* Run-on sentence: A sentence that combines two or more independent clauses without proper punctuation or conjunctions.

* Comma splice: A specific type of run-on sentence where a comma is used incorrectly to join two independent clauses.

For example:

Incorrect: The sky was bright blue, it was a beautiful day. (Comma splice)

Correct: The sky was bright blue; it was a beautiful day. (Semicolon)

Correct: The sky was bright blue. It was a beautiful day. (Period)

Correct: The sky was bright blue, and it was a beautiful day. (Comma and conjunction)