traffic /ˈtræfɪk/ noun [U]
CARS ETC › the cars, trucks, etc using a road: Traffic is heavy (= there are a lot of cars, etc) in both directions. a traffic accident Sorry we're late - we got stuck in traffic.
PLANES AND SHIPS › the planes or ships moving around an area: air traffic control
ILLEGAL › the illegal buying and selling of goods, such as drugs, weapons, etc: the traffic in illegal drugs