Platonic year: Meaning and Definition of

Platon'ic year'

Pronunciation: [key]
— Astron. Astron.
  1. a period of about 26,000 years, equal to the time required for a complete revolution of the equinoxes. Also calledCf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.