Abaft -- Behind, closer to the boat’s rear (“Stern”)

Abeam – Positioned at a right angle to the centerline (“Keel”) of the boat, but not on the boat itself

Aboard -- In or on the boat

Above Deck -- On top of the deck, but not over it (that would be “Aloft”)

Abreast -- Nearby, side by side

Adrift -- floating unattached to the shore or the bed

Aft -- Nearer the boat’s “Stern,” toward the rear

Aground -- resting on or touching the bottom or ground  

Ahead -- Toward the ship’s front (the”Bow”)

Aid to Navigation -- Man made technology used to guide the ship by and supplement natural means (stars, landmarks, etc.)

Alee – In the direction opposite the way the wind blows as opposed to “Windward”

Aloft -- Overhead, above the actual boat

Amidships – At the boat’s center, along the “Keel”

Anchorage -- A fitting location for the anchor, accounting for the current, wind, etc.

Astern -- At the boat’s rear (“Stern”)

Athwart -- At a right angle to the “Keel”

Aweigh -- An anchor’s position when it has just been pulled clear of the bottom