precession

Concise Oxford English Dictionary © 2008 Oxford University Press:
precession/prɪˈsɛʃ(ə)n/

▶noun

• 1 Physics the slow movement of the axis of a spinning body around another axis.

• 2 Astronomy the slow retrograde motion of the equinoctial points along the ecliptic, resulting in the earlier occurrence of equinoxes each year.

– derivatives
precess verb,
precessional adjective.

– origin C16: from late L. praecessio(n-), from praecedere (see precede).