I. ˈriˌprap noun
Etymology: from obsolete riprap sound of rapping, reduplication of rap (I)
1. : a foundation or sustaining wall of stones thrown together without order (as in deep water, on a soft bottom, or on an embankment slope to prevent erosion)
2. : stone used for riprap
II. transitive verb
: to form a riprap in or upon : strengthen or support with a riprap
raprapped the breakwater with stone