Tailback and Traffic

Tailback noun - (American football) the person who plays tailback.

Traffic and tailback are semantically related In some cases you can replace term "Traffic" with "Tailback", this nouns are similar.

Traffic noun - The buying and selling of goods especially on a large scale and between different places.

Tailback and traffic are semantically related in congestion topic. Sometimes you can use "Tailback" instead a noun "Traffic".