Meaning of “traffic” - Learner’s Dictionary

traffic

noun [ U ] us uk /ˈtræfɪk/
The traffic can be a real nightmare after 4.30.Wouldn't it be more sensible to leave before the traffic gets bad?We need more roads to accommodate the increase in traffic.The police were diverting traffic away from the town.Most people are in favour of reducing traffic in cities.
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)