Structures extending from the shoreline out over the sea or tidal river, to protect or partially enclose a harbor and form a landing place for vessels, or to serve as a recreational or entertainment place. A pier may also be a projecting landing stage or jetty on the bank of a river or lake. For structures built along or parallel to the shoreline serving as landing, loading, or unloading places for vessels, use "wharves" or "quays."

Source: Art & Architecture Thesaurus
http://vocab.getty.edu/page/aat/300120779