Breastwork and Rails

Breastwork noun - Fortification consisting of a low wall.

Rails and breastwork are semantically related. In some cases you can replace term "Rails" with "Breastwork", this nouns are similar.

Rails noun - A bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll.

Breastwork and rails are semantically related. Sometimes you can use "Breastwork" instead a noun "Rails".