a window in a ship or airplane
an opening (in a wall or ship or armored vehicle) for firing through
A sealed round window in the side of a ship.
the round window on a ship.
Nautical term describing a circular or round ship's window.
Circular "window" in the side of the ship's hull or superstructure. Most cruise cabins today feature picture windows, full-length glass windows, French balconies, or balconies.
A small, usually circular opening in the side or cabin of the vessel.
circular openings in a ship's hull for ventilation and light
A window in the side of a boat, usually round or with rounded corners. Sometimes portholes can be opened; sometimes they are fixed shut.
A porthole is a small, generally circular, window used on the hull of ships to admit light and air. Porthole is actually an abbreviated term for "porthole window". Though the term is of obvious maritime origin, it is also used to describe round windows on armored vehicles, aircraft, automobiles (the Ford Thunderbird a notable example), and even spacecraft.