Top Definition
Growing up with a sibling of the same age or in the same grade that came about through the parent's remarriage.
My life forever changed the day I became a step-twin.

We don't know what our parents were thinking having step-twins.

Parent to school: Please don't put the step-twins in the same class next year. We don't think it'd be a very good idea at all.

Step-twins are the ultimate fraternal twins, as they not only came from two different eggs, but also two different mothers and two different fathers. Thus, step-twins almost never look alike.
by Harmony08 December 16, 2010

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt
Two babies born simultaneously to two different women, but with the same father.
We have the same birthday because we're steptwins, but our moms hate each other!
by kronq November 06, 2009

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt