My instinct is that it's probably short for Rosalind or Rosalyn or something similar. It's not bad, but kind of dated. I kind of like Ross for a guy, but I also have Chandler on my list, so...
Oh, okay. In all honestly I don't feel passionately enough about Ross as a masculine name to care about it being used on the "wrong" gender. At least she isn't Bruce or Thomas or something.