Definitions of traffic:

• noun:   buying and selling; especially illicit trade
• noun:   the amount of activity over a communication system during a given period of time

  Example: "Heavy traffic overloaded the trunk lines"

• noun:   the aggregation of things (pedestrians or vehicles) coming and going in a particular locality during a specified period of time
• noun:   social or verbal interchange (usually followed by `with')
• verb:   trade or deal a commodity

  Example: "They trafficked with us for gold"

• verb:   deal illegally

  Example: "Traffic drugs"