Meaning of sunspot cycle

sun'spot cy"cle

Pronunciation: [key]
— Astron. Astron.
  1. the cycle, averaging in duration slightly more than 11 years, in which the frequency of sunspots varies from a maximum to a minimum and back to a maximum again.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.