alongside or abreast; opposite the center of the side of the ship or aircraft.
the first lieutenant was ordered to open fire with the eighteen- pounder. carefully the gun was laid, and as the order "fire" was given, down came our english flag, and the stop of the stars and stripes was broken at the gaff. the first shot touched the water abeam of the chase and ricochetted ahead of her. she showed the spanish flag. the captain of the gun was ordered to elevate a little more and try again. the second shot let daylight through her fore topsail, but the third was wide again. infoplease.com