from the GNU version of the Collaborative International Dictionary of English
- n. One half of a shutter made in two parts for closing a porthole.
from The Century Dictionary and Cyclopedia
- n. Nautical, one of the two parts (called upper and lower half-ports) into which is divided a shutter having a semicircular hole to fit round a gun, and serving to close a port in a ship.
Sorry, no etymologies found.