sibcest 

Incest between siblings in fanfiction. Siblings + incest = sibcest.

For example Éowyn and Éomer in lotr.

sibcest by brat July 3, 2004

sibcest 

It uses to describe the deep,pure,bound by blood beautiful romantic love between brother & sister(s) and/or sister(s) & sister(s)

No matter what, She and her brother are so in sibcest, that they've got married.

sibcest by ßß August 30, 2025

sibcest 

use to describe the pure, deep, beautiful & bound by blood, romantic love between siblings.

She was so in sibcest with her brother, that they were inseparable.

sibcest by anonymous August 31, 2025

sibcest 

use to describe the pure, deep, beautiful & bound by blood, romantic love between siblings.

She was so in sibcest with her brother, that they were inseparable.

sibcest by ßß August 31, 2025

Siscest 

Incest between sisters. No brothers allowed.

Siscest is between a specific set of sisters. Twins (Identical or Fraternal), full, half, & three-quarter (horizontal or vertical). Sisters that are excluded step, foster, and adoptive.

Our successful siscest relationship has flourished greatly due to the lack of parents.

Notice: siscest sounds like success.

The best incest is siscest, wincest.

Keep up the siscest you two, you'll have a future in Hollywood.

Siscest by a super secret moose January 16, 2017

Sincest 

A sinful/smut drawing of to relatives.

Guy 1: “Did you hear about Guy 3’s newest Sincest?”
Guy 2: “Ew yeah, it’s disgusting.”

Sincest by SweetIndeed July 30, 2020