look up any word, like rockabilly girl:
 
1.
The leader of any kind of party who makes the decisions even a party such as an xbox live party. The partyfamilias can also be someone who inherently starts or leads a party. Usually decisions are made by the partyfamilias.
Comes from the ancient roman paterfamilias who was the head of an extended family
The Partyfamilias tells people what to do at the party.
by The Wikipedian January 16, 2012