Ship motions

Ship motions are defined by the six degrees of freedom that a ship, boat or any other craft can experience.

The vertical/Z axis, or yaw axis, is an imaginary line running vertically through the ship and through its centre of gravity. A yaw motion is a side-to side movement of the bow and stern of the ship.

The lateral/Y axis, transverse axis, or pitch axis is an imaginary line running horizontally across the ship and through the centre of gravity. A pitch motion is an up-or-down movement of the bow and stern of the ship.

The longitudinal/X axis, or roll axis, is an imaginary line running horizontally through the length of the ship, through its centre of gravity, and parallel to the waterline. A roll motion is a side-to-side or port-starboard tilting motion of the superstructure around this axis.

There are three special axes in any ship, called vertical, lateral and longitudinal axes. The movements around them are known as roll, pitch and yaw.

There are methods for both passive and active motion stabilization used in some designs. They include static hull features such as skegs and bilge keels, or active mechanical devices like counterweights, antiroll tanks and stabilizers.

...
Wikipedia