TMZ has learned her name is Annalisa Azaredo, and she lives in Sydney ... where Nick's currently on vacay with his brother, Joe. She's the epitome of beauty AND brains, too, having studied biomedical sciences at the University of Melbourne.

Annalisa's well-balanced though -- she knows how to have a good time, as you can see in the pics.

We broke the story ... Nick and Annalisa had a pretty hot date, spending the entire day together, despite her having a bloody cycling accident. Good thing they toughed it out .. the date ended with a bang.