[rip.rap] n [obs. riprap sound of rapping] (1833) 1: a foundation or sustaining wall of stones or chunks of concrete thrown together without order (as in deep water); also: a layer of this or similar material on an embankment slope to prevent erosion
2: material used for riprap
[2]riprap vt (1848) 1: to form a riprap in or upon
2: to strengthen or support with a riprap