General terms:
* Grammatically incorrect sentence: This is a neutral and straightforward way to describe a sentence with grammatical errors.
* Ungrammatical sentence: This is another neutral term that emphasizes the lack of correct grammar.
* Flawed sentence: This is a more general term that can encompass grammatical errors as well as other issues like unclear meaning or poor style.
More specific terms:
* Sentence fragment: A sentence that lacks a subject or a verb, or both.
* Run-on sentence: A sentence that combines two or more independent clauses without proper punctuation or conjunctions.
* Comma splice: Using a comma to join two independent clauses without a conjunction.
* Misplaced modifier: A phrase or clause that modifies the wrong part of the sentence.
Informal terms:
* Broken sentence: This is a casual way to describe a sentence with grammatical errors.
* Bad grammar: This is a general term that describes any grammatical error, not just a single sentence.
Ultimately, the best term to use will depend on the specific situation and the level of formality required.