[ red-let-er ]
/ ˈrɛdˈlɛt ər /


marked by red letters, as festival days in the church calendar.
memorable; especially important or happy: a red-letter day in his life.

Origin of red-letter

late Middle English word dating back to 1400–50 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for red-letter