An adult male who acts like part of the family to is friends' children, and usually the most entertaining adult at any get-together. Derived from friend+uncle
Go play ball with Fruncle Matt. Mommy's getting her drink on.
by LexiCodger December 15, 2011
1 more definition
Adult friend of your family that you've come to thing of as an uncle.
That's my fruncle. He isn't really my uncle but he's been a friend of the family my whole life.
by Serialseb May 24, 2007