kırmızı mektup gün

listen to the pronunciation of kırmızı mektup gün
التركية - الإنجليزية
red letter day
A particularly significant day (personal or sectarian), usually very positive, sometimes very negative

In the meantime, the St. Valentine's Day Massacre at Chicago was a red-letter day in the gangster wars..

very special day, special occasion, auspicious day, day that is worthy of notice; important day that will always be remembered; day in a diary of a woman which is marked with a secret mark to indicate the start of her menstrual period