quarter sister 

The half sister of my half sister or half brother.

Amy and Randy had Josie. Randy and Patty had Vanna. Patty and Bob had Andy.

Vanna is Josie's half sister.
Vanna is Andy's half sister.
Josie is Andy's quarter sister.
Andy is Josie's quarter brother.

quarter sister by onegreenfroggie August 15, 2009

Stepish Sister

The daughter of your dad's (or mom's) significant other.

When I visit my dad I stay in my stepish sister's room.

Stepish Sister by Cowboy Pete August 22, 2010

menstrual sister 

one of two (or more) women who happen to fall on the same menstrual cycle. Menstrual sisters often times find comfort in sulking, eating, complaining, and causing a scene together.

My menstrual sister, from the stall next to mine, threw a tampon at me as I kicked my door in anger.

As a good menstrual sister, I shared my chocolate as we bled and weeped together.

menstrual sister by PrincessGaylordFocker December 11, 2016

elevator sister 

A sister or sibling that is your dads but not your moms.

hey have you met my elevator sister

elevator sister by gaye/marshmallow_king February 14, 2017

italian sister 

When you receive a blowjob from a dude in the dark with a mustache but it doesn't count as being gay because you cannot see it.

Last night I got an Italian sister from Frank.

italian sister by The real White Fury October 9, 2017

honey sister

When someone is a closet lesbian this is what they refer to their secret lover or "friend" as.

"Hey everyone this is Jessica, we are like sisters!" Jessica: "Yea, we are totally honey sisters."

honey sister by ButtMuffeen November 1, 2017

Leap Sister 

Your Brother-In-Law's wife, or your wife's brother's wife.

My leap sister is a total psycho, I feel bad for my brother-in-law.

Leap Sister by pish pishter May 9, 2019