n. [ Cf. Rap. ] (Masonry) A foundation or sustaining wall of stones thrown together without order, as in deep water or on a soft bottom, or in a river channel. [ 1913 Webster +PJC ]

v. t. [ imp. & p. p. Riprapped p. pr. & vb. n. Riprapping. ] To form a riprap in or upon. [ 1913 Webster ]