A structure, usually massive, on the seaward side of a harbour for its protection against current and wave action, drift ice, sanding up, wind etc. It may be possible to walk or drive along the mole. It may also sometimes be suitable for berthing of ships.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM