Sphere rotating around one of its diameters
Rotation, precession, and nutation in obliquity of a planet
An example of rotation. Each part of the worm drive—both the worm and the worm gear—is rotating on its own axis.
Yearly changes in the location of the Tropic of Cancer near a highway in Mexico

Nutation is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism.

- Nutation

The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession.

- Rotation around a fixed axis
Sphere rotating around one of its diameters

1 related topic

Alpha

Precession of a gyroscope

Precession

Change in the orientation of the rotational axis of a rotating body.

Change in the orientation of the rotational axis of a rotating body.

Precession of a gyroscope
The response of a rotating system to an applied torque. When the device swivels, and some roll is added, the wheel tends to pitch.
Apsidal precession—the orbit rotates gradually over time.

In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself.

A motion in which the second Euler angle changes is called nutation.