- an act or instance of nodding one's head, especially involuntarily or spasmodically.
- spontaneous movements of plant parts during growth.
- the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes.
- the variation of the inclination of the axis of a gyroscope to the vertical.
- a periodic variation in the precession of the earth's axis causing the earth's poles to oscillate about their mean position
- a periodic variation in the uniform precession of the axis of any spinning body, such as a gyroscope, about the horizontal
- the spiral growth of a shoot, tendril, or similar plant organ, caused by variation in the growth rate in different parts
- the act or an instance of nodding the head
