siblingness 

When siblings share physical similarities. Similar to the word "lookalike" but specifically used to describe siblings.

"Very similar face, I can see the siblingness"

siblingness by aceofaces January 21, 2009

siblingversary 

The anniversary when you first met your long lost sibling.

Kassey, Hannah and Jake celebrate their siblingversary on the day they found each other.

siblingversary by Woahkasable January 28, 2021

Siblingnisum 

When your parents choose one sibling and is always on their side for everything. They can never do anything wrong. Think of it as sexism and racism

Mom: Tommy you are such a good boy

Me: What! I'm good too!
Mom:...
Me: This is complete siblingnisum

Siblingnisum by OWO777 November 10, 2021

Simpingness 

When someone’s heart is full with too much love and power to keep away from the one who gave them that power. Dr. Michael Morbius is the #1 person that people have simpingness for.

“Wow, I can’t believe you’re out and about after all that simpingness that was going on.

Simpingness by Doodoocacarat👹 June 27, 2022

Siblingcest 

Some fucked up shit Duncan came up with watching Mashle

That freak is into siblingcest

Siblingcest by 6789fghj June 16, 2025