monitor nozzle

Etymology
From the resemblance of the rotable nozzle installation and its degrees of freedom of movement to that of the gun turret on a monitor (the type of warship).

Noun

 * 1) A nozzle firmly mounted to a vehicle or structure and capable of turning completely round in a horizontal plane while having a limited play in a vertical plane, used in hydraulic mining, fire-extinguishing apparatus, etc.