adoptiversary 

combined from adoption and anniversary...used to to denote the anniversary of adopting a kid or a furkid.

Often celebrated like a birthday.

Tomorrow is me and Fido's adoptiversary...it is 3 years since I picked him up at the shelter

adoptiversary by daveholman May 1, 2009

abortiversary

The anniversary of the day you aborted a fetus, known to some as a "child."

This is typically a day of very dark reflection, either because of the act itself or the hoops you were forced to jump through as a result of knocking up a very crazy and hormonal young tramp.

Tomorrow is our abortiversary. When I say "our," I mean me, that crazy chick to whom I will never speak again, and that cluster of cells that at the bottom of a biohazard bag.

What am I doing for my abortiversary, you ask? I'm going to go get shit-faced, hopefully resulting in some permanent amnesia that will encompass said abortion.

My near-baby-mama wants to know what we should do to celebrate our abortiversary. I suggested getting her a hysterectomy.

abortiversary by WayneGretzky February 16, 2010

adultiversary 

The annual recognition of the date that two people, at least one of whom is married, began their extramarital tryst.

Jack and Jill have been married for ten years, but Jill is about to celebrate her three-year adultiversary with her sancho Matt.

adultiversary by Anon21412 May 20, 2014