Definition of “traffic” - Learner’s Dictionary

traffic

noun [ U ] uk us /ˈtræfɪk/
CARS ETC

A2 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

(Definition of “traffic” from the Cambridge Learner's Dictionary © Cambridge University Press)