Perpendicular to a boat's centerline

late 15c., from a- (1) + thwart.

adv. From side to side.

Across. In opposition to.

(adv) at right angles to the center line of a ship(adv) at an oblique angle

Running from side to side. At right angles to the fore and aft or centerline of a ship.

At right angles to the fore and aft or centerline of a ship; A direction across the width of a vessel.

Same as a beam

 Lying along the ship's width, at right angles to the vessels fore-and-aft line (centerline). Same as abeam. B

    Across; at right angles to.  

From side to side; crosswise or perpendicular to the keel.

Lying along the ship's width, at right angles to the vessels fore-and-aft line (centerline). Same as abeam.

At right angles to the fore and aft or centerline of a ship

Across. Transversely.

Across

Lying along the ship's width, at right angles to the vessels centerline

At right angles to the fore and aft or centerline of a ship

At right angles to the fore and aft or centerline of a ship

A member or dimension running from port to starboard.

Transversely, at right angles to fore and aft ; across the keel. Athwartship is thus across the ship from one side to the other. Athwart hawse is when one vessel gets across the stem of another.

Or "athwartships." Across the ship, from side to side. Across anything, really, as in: "Wow, honey. Little Billy's foot measures five inches athwart!"

across; from side to side; transversely