naper > groyne, cut-off bund, bund, apron, wave trap
(Vukićević B, Građevinski rečnik)

naper (gat, molo, paralelna građevina) > training bank, training groyne, groyne, jetty, baffle pier
(Živković dr S, Građevinski rečnik)

molo > jetty
(http://www.eudict.com/?lang=croeng&word=molo)

gat > jetty, mole, quay, wharf
(http://www.eudict.com/?lang=croeng&word=gat)


Webster's Online Dictionary
- GROYNE
Noun
1. A protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away.
…
A structure built from the bank of a stream in a direction transverse to the current in order to prevent bank erosion
(http://www.websters-online-dictionary.org/definition/groyne)
- JETTY
Noun
1. A protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away.
A structure built from the bank of a stream in a direction transverse to the current in order to prevent bank erosion.
A floating platform, usually anchored at the end of a wharf or pier, for the landing or embarking of passengers and goods.
A structure (e.g.; a pier, or mole of wood or stone) extending into a sea, lake, or river to influence the current or tide or to protect a harbor.
A. An engineering structure (such as a breakwater, groin, seawall, or small pier) extending out from the shore into a body of water, designed to direct and confine the current or tide, to protect a harbor, or to prevent shoaling of a navigable passage by littoral materials. Jetties are often built in pairs on either side of a harbor entrance or at the mouth of a river b. A British term for a landing wharf or pier used as a berthing place forvessels.
(http://www.websters-online-dictionary.org/definition/jetty)