1. A portmanteau of "borderline" and "whore." The act of displaying sluttish characteristics while falling short of actually being a promiscuous whore.
2. Promiscuity conducted with very high standards, proper hygiene and caution.
1. She's really whorderline. I swear dude, she acts like a total cumdumpster, but her self-control is impeccable!
2. Yes, you have lots of sex. Yes, you're responsible about it and pull it off admirably. Still? Kinda whorderline.