Sexaversary 

The anniversary of the day one loses their virginity.

This is my three year sexaversary!

Sexaversary by reezybaby March 9, 2011

semiversary 

6 month aniversary.

A shortened version of the word semianniversary.

On the inside of a card:
Happy semiversary

semiversary by KoH March 20, 2007

Sex-aversary 

The anniversary of the first time you and your partner had sex.

"Oh babe happy sex-aversary"

Sex-aversary by LuvernotFiter May 20, 2010

Sexiversary 

The date on which two people first had sex.

He was invited out for a drink after work, but he knew that since it was their sexiversary and she would be expecting him to be on his game, he declined.

Sexiversary by Kate Charlton June 18, 2008

Sadaversary 

The day of a national tragedy.

November 8th, 2017, the nations first sadaversary, marks the day Donald J. Trump won the election for the presidency.

Sadaversary by Kiflaam April 20, 2018

Sexiversary 

The date on which two people first had sex.

He was invited out for a drink after work, but he knew that since it was their sexiversary and she would be expecting him to be on his game, he declined.

Sexiversary by Kate Charlton June 19, 2008

sexversary 

the anniversary of the day you had sex. most easily observed once pregnancy begins; in this sense, also known as conception day.

"happy sexversary, friend with benefits!"

"wow, amy and tom! happy sexversary, and welcome to the third trimester."

sexversary by janice jim July 13, 2009