dyke
n. countablen. a wall or bank built to keep water out of an area. In some contexts, it is also a very offensive word for a lesbian, so you should be careful with it.
n. a barrier or embankment constructed to prevent flooding from the sea or a river; also used as a derogatory slang term for a lesbian, though sometimes reclaimed within the community.
The workers built a dyke to protect the village from the rising river.
Engineers reinforced the coastal dyke system after the storm surge nearly breached the existing defenses last winter.
The low-lying reclaimed land is protected by an intricate network of dykes and pumping stations that have functioned effectively for centuries.
In its geological sense, it refers to a vertical sheet of rock that cuts across older layers.