rip-rap or riprap /ripˈrap/

1. Loose broken stones, used to form a foundation on soft ground or under water, or in the construction of revetments and embankments
2. A foundation formed of these

• backvelder
• backvelders
• backvelds
• backward
• backward and forward
• backwardation
• backwardations
• backward-looking
• backwardly
• backwardness
• backwardnesses
• backwards
• backwards-compatible
• backwash
• backwashed
• backwashes
• backwashing
• back water
• backwater
• backwaters
• backwoods
• backwoodsman
• backwoodsmen
• backword
• backwords