jetty (n.)

early 15c., from Old French jetee, getee "a jetty, a pier; a projecting part of a building," also "a throw," noun use of fem. past participle of jeter "to throw," from Latin iacēre "to lie, rest," related to iacere "to throw" (from PIE root *ye- "to throw, impel"). The notion is of a structure "thrown out" past what surrounds it.