nutation
noun
nu·ta·tion nü-ˈtā-shən 
nyü-
1
archaic : the act of nodding the head
2
: oscillatory movement of the axis of a rotating body (such as the earth) : wobble
3
: a spontaneous usually spiral movement of a growing plant part
nutational
nü-ˈtā-sh(ə-)nəl
adjective nyü-
Word History
Etymology
Latin nutation-, nutatio, from nutare to nod, rock — more at numen
First Known Use
1612, in the meaning defined at sense 1