abbrevation of visible bra line, which denotes that you can see that someone is wearing a bra, because the edges can be seen through the upper layers of clothing, or when the tank top above (or anything alike) does not cover the bra properly. This is something women would want to avoid - but men most certainly like a good VBL.
"Oh sweetie, that's not the right bra for you! I can see your VBL right through that blouse."
by Monticello-W December 26, 2012