资料来源 : pyDict

垂头,下垂,俯下,章动

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Nutation \Nu*ta"tion\, n. [L. nutatio a nodding, fr. nutare to
   nod: cf. F. nutation.]
   1. The act of nodding.

            So from the midmost the nutation spreads, Round and
            more round, o'er all the sea of heads. --Pope.

   2. (Astron.) A very small libratory motion of the earth's
      axis, by which its inclination to the plane of the
      ecliptic is constantly varying by a small amount.

   3. (Bot.)
      (a) The motion of a flower in following the apparent
          movement of the sun, from the east in the morning to
          the west in the evening.
      (b) Circumnutation.

资料来源 : WordNet®

nutation
     n : uncontrolled nodding