Foxy Brown is FURIOUS over reports she trashed Jay-Z ... telling TMZ she NEVER referred to Hova as a gonorrhea-infected "tranny chaser" ... and now she's threatening to sue.
Brown is referencing a report that first appeared on MediaTakeOut -- which says Foxy recently went to a baby shower and started dishing about Jay-Z's sex life to one of the guests -- saying he secretly engages in gay sex ... and that she lost her virginity to him when she was 15 and he was 27.
There's more ... including allegations of a robbery, sex tape and STDs.
But Foxy says the report is complete BS, telling TMZ ... "The atrociousness of this story sickened me to my stomach. Any and everyone involved will be contacted by my attorney."
Foxy says, "In all my years in the music industry, these are the most disgusting and disrespectful allegations I've ever experienced. This fictitious story ... with NO audio, visual or written interview, clearly was concocted with malicious intent."
"Jay has only been wonderful to me and my family, a great friend throughout all the years I've known him and we had nothing but great success as a team."
She continues, "Beyonce, his wife, has always been gracious and sweet to me ... I will NOT let any undercover hater create discord and disrespect my name and reputation."
"This disrespect will NOT be tolerated."
Calls to MediaTakeOut have not been returned.