The word 'traffic' arrived in English in the early 16th century with the primary sense of 'trade' or 'commerce', particularly the transportation and exchange of merchandise. This commercial origin is preserved in terms like 'drug traffic'. The semantic evolution from 'trade' to 'movement of vehicles' is logical, as commerce inherently involves the transit of goods. By the early 19th century, the term had generalized to refer to the movement and passage of people and conveyances along roads and routes, which is its most common meaning today. Thus, a word rooted in the concept of commercial exchange broadened to signify the flow and circulation inherent in modern transport systems.

The word is a simplex loanword. It entered English from the French word 'trafic', which itself derived from the Italian 'traffico'. The ultimate origin is uncertain but may be from the Vulgar Latin 'transfricare' (to rub across) or 'trafficare' (to engage in trade), influenced by the Arabic 'tafrīq' (distribution).