English
gun barrel tank
From gun barrel + tank, from the shape of the tank, which is long and cylindrical, like the barrel of a gun.
A compound of gun barrel + tank
Portuguese tanque ‘tank, liquid container’
English tank
Today it means
noun A long slender cylindrical metal tank, especially one used to separate oil from water as it flows from a production well.
Language periods are conventional ranges, not dates for this word.
Etymograph / gun barrel tank