Top Definition
The sister of one's spouse who acts in a purely selfish and ultimately evil fashion, working to create strife within a family to their own ends, whether emotional manipulation, financial gains, or perhaps both. She has the same motives and machinations as the Sith, or Evil Jedi, from the Star Wars galaxy.
"I found out my sither-in-law has been actively seeking to turn family members against my husband and I, hoping that it will somehow result in her getting a larger inheritance."
by kitschicat August 29, 2012

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