Yes, Brielle is a short form of Gabrielle. Personally, I do not like Gabrielle (I also dislike the nn Gabby, which is probably the reason I dislike it), but I really love Brielle. Just so you know, babynames.com isn't a reliable site - a lot of their names are made up origins and meanings so I would advise if you want a real meaning, go to a site that breaks it up in its orignal language (this website does that for many names). According to the Bible, where the name Gabriyel (the original form of Gabriel/Gabrielle) comes from, the name is Hebrew and means "strong man of God." Because that is the origin of the name, I would assume this is the actual meaning. Not to say that I do not believe that other languages have similar-sounding names with very different meanings, but I have not yet found a reliable source with a different meaning and origin.