courtesy sister 

A friend(no 'benefits') who's so close she's like a sister, or just is the mother of someone who calls you Uncle. (could be a former sexual partner, but who is only a friend now)

How many siblings do you have?

Well, I have 2 brothers, 2 sisters from my mom, & a half brother from my dad, & a courtesy sister I stilll keep in touch with.

courtesy sister by cyberpope67,BC,Canada May 2, 2021

half-sister 

Female person who, in relation to the other, has a one parent in common and a different one parent.

My half-sister is a good person.

half-sister by Usery May 3, 2021

Ur Sister 

The person I did last night

John: I saw u in my house last night
Carmine: yea I was doing ur sister
John: GET THE FUCK OVER HEAR

Ur Sister by Iwasinurmom May 13, 2021

sussy sister sas 

The one type of sister who is always suspicious and very sassy

Girl 1:my sister is always sussy sister sas

Girl2: yes ikr

sussy sister sas by Sapphire >3< May 23, 2021

older sister aunt

A person which is not blood related to your family, but acts like both an older sister and a cool aunt. She fits right in to your family as if you are blood related.

Lara is our older sister aunt.

older sister aunt by ohlala1010 June 30, 2021

shit sister

every family has one....the less favourite or popular or successful sibling. Think of Danni Minogue compared to Kylie. Danni is the shit sister. Could also, be the second favourite son, if you have a brother.

Danni is the shit sister to Kylie.

shit sister by HomeBrand August 30, 2021

Best sister 

Jeslin

Jeslin is the best sister ever tf

Best sister by NotJosue😳 September 2, 2021