Reference

A & A
An abbreviation for alterations and additions. It refers to changes to the structure, rigging and equipment of a warship.
A.J. Squared-Away
A USN term that refers to the mythical sailor who is perpetually well-organized.
AAW
An acronym for Anti-Air Warfare.
Aback
1. Creating a braking effect by turning a sailing ship so the wind hits the forward face of the sail. When done accidentally, the same effect is extremely detrimental to the forward momentum of the vessel.
2. This term is used when a sailor is suddenly confused or surprised. E.g. “Bloggins was all aback when he saw he was suddenly assigned to the duty watch.”
Abaft
The correct term to use when indicating a direction toward the stern. e.g. “Bloggins placed the heaving lines abaft of the gun.” The phrase "aft of" is not correct.
Abaft the Beam
When describing an object away from the ship, this term is used to say the direction is further aft than the beam; i.e. a relative bearing greater than 90 degrees from the bow. e.g. "The man in the water lies on the starboard side, just abaft the beam.”
ABC
The acronym once used for "Atomic, Biological, Chemical". It was eventually replaced by "NBC" (Nuclear, Biological, and Chemical).
Abeam
Referring to a relative bearing at right angles to the centerline of the ship's keel.
Able Seaman
A junior rank in the navy, equivalent to the rank of Private in the Army or Air Force. Derived from the term "Able Bodied Seaman", the rank insignia is a single chevron.
About
A term used to describe the act of changing the course of a sailboat by tacking. The words “ready about” or “boutship” are used to prepare the hands for the tacking manoeuvre.
Above Board
Not hiding anything. A transparent state where everything is in the open. This term was originally used to describe the ship’s belongings that were on or above the main deck, and in plain view.