Meaning the face of the wheel will push out toward the middle and the "arms" will bend inward- possibly more than the picture above, which tends to give the wheels sort of a "starfish" kind of look.
This is the opposite of concave wheels, where the spokes bend away from the hub (toward the outside of the car), which is currently a pretty popular style.
since our offsets are so high, the hub juts out from the car pretty far. in order to get a lip for wheels with offsets like these, the manufacturer has to make the spokes dive inward toward the car body.
concave (big picture so i wont embed, just click):
http://www.300cforums.com/forums/att...concave360.jpg
convex:
http://www.ridelust.com/wp-content/u...ceWheels_5.jpg