GROYNE, a framed structure of timber or a low wall of masonry or concrete run out over a foreshore into the sea, in a direction approximately at right angles to the coast line, for the purpose of arresting the lateral travel of sand and shingle and thus raising the foreshore level as a barrier against the encroach ment of the sea. On the coasts of Holland and Belgium low groynes constructed of fascine mattress-work and rubble stone are commonly employed. Groynes similar in form to those used on sea-shores, and also, in many cases, built up of rubble or fascine work, are employed for training the flow of rivers, pro tecting their banks from erosion, and deepening their channels. Such groynes are built out over the river banks and bed trans versely to the flow of the current and are termed spur-groynes (see RIVER AND RIVER ENGINEERING). The word groyne ap pears to have been used originally to denote any wall run out transversely to the shore. In the United States of America the word is spelt groin both in architecture and as applied to sea defence works. (See COAST PROTECTION AND LAND RECLAMA TION.) (N. G. G.)