when something is silly and hilarious at the same time and you can't make up your mind on which word you want to say, this word is most likely to naturally come out of your mouth.
Tim: “You must like getting spanked Farley, I guess it runs in the family.”

Jillian: "ha! that was sillarious!

Kid: "SHUT UP!...SHUT UP!"
by Tinbug January 5, 2010
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An adjective used in front of Hillary when she is being silly.
by Gamepal Randy March 22, 2006
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