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1.
An acquaintance that you invite to important functions such as weddings and baby showers, but wouldn't normally hang out with otherwise. Like a carnation is a filler flower in a bouquet, the filler friend gives out the illusion that you have more friends than you actually do.
Since my fiance invited all of his hockey team to our wedding, I sent out an invitation to all of my filler friends so that I won't look like a loser with no friends at my wedding.
by Pixie 55 November 23, 2008
 
2.
A friend who is used as a filler in social situations.

1. Having a party and inviting your filler friends just so there are more people, to make the party look more full.

2. Inviting a filler friend to a movie because you don't want to go alone.

"Hey I got an extra hockey ticket, ya wanna go with me?"
by Sarah Bunker October 25, 2008
 
3.
When someone that you barely know has no one they usually hangout with at a social event of some sort, and start acting like your friend.
I'm so tired of being a filler friend >.>
by ...o.o October 26, 2010