Here's the deal ... the singer-songwriter was originally sued back in June by an unnamed woman for allegedly exposing her breast at a Connecticut casino back in 2013.

This is an allegation she initially floated in 2022 through a demand letter to him, but didn't officially sue until Summer 2023. In her original demand letter, she was asking for north of $5 million to settle it out of court -- but he never played ball, so she ended up suing civilly.

You'll recall ... this woman -- who filed as a Jane Doe in her suit -- claimed Songz had pulled out her breast from her bathing suit top during a "Foxwoods Liquid Sundays with Trey Songz" event and even claimed there was video evidence to back up her claim.

She alleged it was done without her permission, and that it amounted to sexual assault -- something Trey and his team had been vehemently denying from the very beginning.

Anyway, this lady amended the original complaint in July -- and then again in September before Songz filed a motion to dismiss saying the statute of limitations barred her claim ... which the judge granted, although he gave her another chance to amend it a 3rd time.

She did exactly that, but her renewed claims looked incredibly similar to the earlier ones ... prompting Songz to file another motion to dismiss. That was back on December 29 when he did that ... and apparently, Doe never responded to Songz's motion to dismiss this time.