1. In the past, special days would be marked with red letters making it a red letter day

2. Any day with personal significance

3. A day that you make someone else's day wonderful through various ways
1. Oh look, it's the queens birthday tomorrow. Better get ready for the red letter day!

2. Oh look, my girlfriends birthday is coming up. Better get ready for the red letter day!

3. I went with my girlfriend shopping and bought her everything she wanted, then we had a candlelit dinner and finally, I sang her to sleep under the stars. All of this because it was her red letter day
by Quicksilver Elegance December 22, 2008
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a memorably happy or noteworthy day
When Jack comes home from his tour of duty, that'll be a red-letter day.
by johnpqrtst July 15, 2005
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1. A particularly enjoyable or important occasion.

2. The day a woman menstruates.

3. In the Harry Potter series, the day one of the students receives a howler, typically in the Main Hall in front of everyone else.
The launch of one's first novel is a red letter day in any novelist's life.

She had her first red letter day last week. She spent all day sulking in her bedroom.

Another red letter day for poor old Ronald.
by Fearman October 25, 2007
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what your Granny called getting your period.
Its Beryls red letter day
by fert April 24, 2003
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