Step Girlfriend 

A woman who dates a man that has children by another woman. The woman is the girlfriend to the father of the children and thus a Step Girlfriend to the children.

The children left their Mom's house to go visit their Dad and Step Girlfriend for the weekend.

Step Girlfriend by Glitterfly78 December 3, 2009

Step-Girlfriend 

Somone who is more than a friend and you love each other but both of you have a healthy relationship with someone else and you know a romantic relationship wouldn't work out between the two of you.

-Bro, wha'chu did last night?
-I don't know. I think I got pretty drunk. I think I've fucked my Step-Girlfriend.
-AYO WHAT? WHAT'S A STEP-GIRLFRIEND?

Step-Girlfriend by Volktron March 11, 2022

Step-Girlfriend 

When your gay husband makes a child with a woman with your permission.

Yesterday I saw my Step-Girlfriend with the child of my husband.

Step-Girlfriend by Volktron March 11, 2022

Step-girlfriend 

A man who is married to a woman who has a daughter with another man in which he then proceeds to date the daughter of his wife; the step-daughter is now the step-girlfriend.

I told my step-girlfriend to wipe the cock tears from her face before her mother got home.

Step-girlfriend by Bamzamma August 22, 2015

step-girlfriend 

A girl who someone dates to get closer to her friend.

With the ultimate goal of dating her friend, you date girl A. When that relationship inevitably fails, you can move onto girl B, whom you have been getting to know throughout the span of the first relationship. Girl A was the step-girlfriend used to get to girl B.

step-girlfriend by Chiakara November 7, 2009