submarine, pigboat, sub, U-boat
['flagpole, flagstaff', 'chiton, coat-of-mail shell, sea cradle, polyplacophore', 'gar, garfish, garpike, billfish, Lepisosteus osseus', 'military uniform', 'beach wagon, station wagon, wagon, estate car, beach waggon, station waggon, waggon', 'safe', 'sliding door']