'Porthole' definitions:

Definition of 'porthole'

From: WordNet
noun
A window in a ship or airplane
noun
An opening (in a wall or ship or armored vehicle) for firing through [syn: port, embrasure, porthole]

Definition of 'Porthole'

From: GCIDE
  • Porthole \Port"hole`\, n. (Naut.) An embrasure in a ship's side. See 3d Port. [1913 Webster]