also riprap, "loose stone thrown down in water or soft ground as foundation," 1822, American English, perhaps connected with earlier nautical word rip-rap meaning "stretch of rippling water" (often caused by underwater elevations), 1660s, probably of imitative origin (compare riprap "a sharp blow," 1570s).
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}