Source : Webster's Revised Unabridged Dictionary (1913)

Riprap \Rip"rap`\, n. [Cf. {Rap}.] (Masonry)
   A foundation or sustaining wall of stones thrown together
   without order, as in deep water or on a soft bottom.

Riprap \Rip"rap`\, v. t. [imp. & p. p. {Riprapped}; p. pr. & vb.
   n. {Riprapping}.]
   To form a riprap in or upon.