Seawall Definition

A seawall is a man made structure made of stone or concrete. It blocks water from getting up into towns and destroying houses.
A problem with seawalls is that the sand will erode away and the seawall will have to be extended farther down into the ground. 
Source: "sea wall - definition of sea wall by the Free Online Dictionary, Thesaurus and Encyclopedia.." Dictionary, Encyclopedia and Thesaurus - The Free Dictionary. N.p., n.d. Web. 9 Jan. 2013. <http://www.thefreedictionary.com/sea+wall>.