What does "porthole" mean?

A gunport; an opening in the hull of a ship through which cannons are fired.

What is a synonym for "porthole"?

Common synonyms include: air hole, armhole, bay, bay window, blowhole, bow window.

Pronounced //ˈpɔː(ɹ)t.həʊl//.

/ˈpɔː(ɹ)t.həʊl/ noun

noun ·Uncommon ·College level

Noun

1
A gunport; an opening in the hull of a ship through which cannons are fired. archaic
2
an opening (in a wall or ship or armored vehicle) for firing through wordnet
3
A circular window set in the hull of a ship.
4
a window in a ship or airplane wordnet

"They saw the waves through the porthole."

From port + hole.