Top definition
A relationship started with someone thought to be a sibling, but who turns out not to be
"-He's got a girlfirend who they all thought was a sister as she's the daughter of the woman who had an affair with their father, but it turned out shes not"
"- thats semicest man"
by Alvinchipa September 02, 2009
Mug icon

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