Base Tint:
A dye embedded in sunglass lenses that creates the color you see when you look at the backside of your shades.
Bridge:
The area that arches up between the lenses over the nose and supports the majority of the weight of the glasses.
Browline:
Retro sunglasses with a heavy browline and thin lower rims. Celebrities like Bruno Mars and Robert Pattinson are often seen sporting this style.