Four-lanes is a word commonly used to describe a road that has two lanes going in opposite directions on both sides of a median. In some situations, it may be useful to use a synonym for this word. Some synonyms for four-lanes include dual carriageway, divided highway, and expressway. Dual carriageway is a type of road that has two lanes going in opposite directions, separated by a median. A divided highway is a road that has a physical barrier separating the two lanes going in opposite directions. Lastly, an expressway is a divided highway with limited access and high speed limits. These synonyms may be useful for describing different types of roads in various contexts.