bluejacket
What does bluejacket mean?
An enlisted sailor in the US Navy ranking E-6 or below — petty officer first class and down. Chiefs (E-7+) and officers are out of the club. The term carries the weight of the working-deck Navy: the people who chip paint, stand watches, and actually run the ship.
Origin
From the dark-blue jumper uniform historically worn by enlisted Royal Navy and US Navy sailors. The US Navy's enlisted handbook is literally called The Bluejacket's Manual, first published in 1902.