Definition of jetties:
(n) :
(architecture) A part of a building that jets or projects beyond the rest; specifically, an upper storey which overhangs the part of the building below.
(n) :
(by extension) A structure of stone or wood which extends into a river or sea to protect a bank, beach, harbour, etc., from currents or tides; a breakwater.
(n) :
(by extension) (nautical) A dock or wharf extending into a river from a bank, or into a sea from a shore, for boats to land or moor at; a pier.
(n) :
(by extension) A natural piece of land projecting into a body of water; a peninsula, a promontory.
(n) :
(by extension) (aviation) In full air jetty: synonym of jet bridge (“an elevated, usually enclosed, corridor connecting an airport to an aeroplane for embarking and disembarking crew and passengers”).
(v) :
(transitive) (architecture) Sometimes followed by out: to construct (a part of a building) so that it jets or projects beyond the rest.