Dual carriageway and Subway

Dual carriageway noun - A highway divided down the middle by a barrier that separates traffic going in different directions.

Subway and dual carriageway are semantically related. In some cases you can use "Subway" instead a noun phrase "Dual carriageway".

Subway noun - An electric railway operating below the surface of the ground (usually in a city).

Dual carriageway and subway are semantically related. Sometimes you can use "Dual carriageway" instead a noun "Subway".