nutation

/njuːˈteɪʃən/
noun
  1. A slow, rhythmic nodding or swaying motion, especially of a plant stem or part of a plant.
    • The nutation of the vine was visible as it searched for support.
    • Gardeners often observe nutation in young sunflowers as they track the sun.
    • The nutation of the bean plant helped it climb the trellis.
  2. A slight, periodic wobble in the axis of a rotating object, such as a spinning top or a celestial body.
    • The spinning top showed a small nutation before it settled into steady rotation.
    • Nutation in a gyroscope can affect the accuracy of instruments.
    • Astronomers measure the nutation of Earth's axis to improve navigation systems.