a calendar devised to be used for many years, as in determining the day of the week on which a given date falls.
a desk calendar with months, days, and dates that can be changed, as by adjusting various dials, so that it may be used over and over for many years.
Origin of perpetual calendar
First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019