the inside of a ship. Hence any person who enters a ship is said to go aboard: but when an enemy enters in the time of battle, he is said to board; a phrase which always implies hostility.—To fall aboard of, is to strike or encounter another ship when one or both are in motion, or to be driven upon a ship by the force of the wind or current.—Aboard-main-tack, the order to draw the main-tack, i.e. the lower-corner of the main-sail, down to the CHESS-TREE.