#8: Nutation

Definition:

: the act of nodding; especially: an involuntary nodding of the head

Example:

"Or else you may see, in your sleep's perturbations,/ Some old and uncommonly ugly relations,/ Who'll be very apt to disturb your nutations/ By unpleasant allusions, and rude observations!" – John Godfrey Saxe, Richard of Gloster (from The Money-King, and Other Poems), 1860

About the Word:

For some reason most of us find it delightful to discover a word that describes a particular phenomenon very specifically, even if we will rarely have need to use the word. Now, if you have a companion prone to nutation, you'll at least have a word to label what you observe.

Nutation comes to us from the past participle of the Latin word nutare, which means 'to nod, sway, or rock.'

In addition to referring to the nodding of the head, nutation has meanings related to 'the vibratory displacement of the axis of a precessing top or gyroscope,' 'a libratory motion of the earth's axis,' and 'an autonomic movement' – in case you need to put someone to sleep by means of verbal skill alone.